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Friday, June 19, 2026

Gmail

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Gmail

Logo since May 2026
 
A screenshot of a Gmail inbox and compose box on Gmail's own webmail interface
Type of site
Webmail
Available in133 languages
OwnerGoogle
Created byPaul Buchheit
URLworkspace.google.com/products/gmail/ Edit this at Wikidata
CommercialYes
RegistrationRequired
Users1.8 billion
LaunchedApril 1, 2004; 22 years ago
Current statusActive
Content license
Proprietary
Written inJava, C++ (back-end), JavaScript (UI)

Gmail is a mailbox provider by Google. It is the largest email service worldwide, with 1.8 billion users. It is accessible via a web browser (webmail), mobile app, or through third-party email clients via the POP and IMAP protocols. Users can also connect non-Gmail e-mail accounts to their Gmail inbox. The service was launched as a beta version in 2004. It came out of beta in 2009.

The service includes 15 gigabytes of storage for free for individual users, which includes any use by other Google services such as Google Drive and Google Photos; the limit can be increased via a paid subscription to Google One. Users can receive emails up to 50 megabytes in size, including attachments, and can send emails up to 25 megabytes in size. Gmail supports integration with Google Drive, allowing for larger attachments. The Gmail interface has a search engine and supports a "conversation view" similar to an Internet forum. The service is notable among website developers for its early adoption of Ajax.

Google's mail servers automatically scan emails to filter spam and malware.

Features

Storage

The Gmail webmail interface as it originally appeared

On April 1, 2004, Gmail was launched with one gigabyte (GB) of storage space, a significantly higher amount than competitors offered at the time. The limit was doubled to two gigabytes of storage on April 1, 2005, the first anniversary of Gmail. Georges Harik, the product management director for Gmail, stated that Google would "keep giving people more space forever."

In October 2007, Gmail increased storage to 4 gigabytes, after recent changes from competitors Yahoo and Microsoft. On April 24, 2012, Google announced the increase of storage included in Gmail from 7.5 to 10 gigabytes ("and counting") as part of the launch of Google Drive. On May 13, 2013, Google announced the overall merge of storage across Gmail, Google Drive, and Google+ Photos, allowing users 15 gigabytes of included storage among three services. On August 15, 2018, Google launched Google One, a service where users can pay for additional storage, shared among Gmail, Google Drive and Google Photos, through a monthly subscription plan. As of 2021, storage of up to 15 gigabytes is included, and paid plans are available for up to 2 terabytes for personal use.

There are also storage limits to individual Gmail messages. Initially, one message, including all attachments, could not be larger than 25 megabytes. This was changed in March 2017 to allow receiving an email of up to 50 megabytes, while the limit for sending an email stayed at 25 megabytes. In order to send larger files, users can insert files from Google Drive into the message.

Interface

The Gmail user interface initially differed from other web-mail systems with its focus on search and conversation threading of emails, grouping several messages between two or more people onto a single page, an approach that was later copied by its competitors. Gmail's user interface designer, Kevin Fox, intended users to feel as if they were always on one page and just changing things on that page, rather than having to navigate to other places.

Gmail's interface also makes use of "labels" (tags) that replace conventional folders and provide a more flexible method of organizing emails; filters for automatically organizing, deleting or forwarding incoming emails to other addresses; and importance markers for automatically marking messages as 'important'.

In November 2011, Google began rolling out a redesign of its interface that "simplified" the look of Gmail into a more minimalist design to provide a more consistent look throughout its products and services as part of an overall Google design change. Substantially redesigned elements included a streamlined conversation view, configurable density of information, new higher-quality themes, a resizable navigation bar with always-visible labels and contacts, and better search. Users were able to preview the new interface design for months prior to the official release, as well as revert to the old interface, until March 2012, when Google discontinued the ability to revert and completed the transition to the new design for all users.

In May 2013, Google updated the Gmail inbox with tabs which allow the application to categorize the user's emails. The five tabs are: Primary, Social, Promotions, Updates, and Forums. In addition to customization options, the entire update can be disabled, allowing users to return to the traditional inbox structure.

In April 2018, Google introduced a new web UI for Gmail. The new redesign follows Google's Material Design, and changes in the user interface include the use of Google's Product Sans font. Other updates include a Confidential mode, which allows the sender to set an expiration date for a sensitive message or to revoke it entirely, integrated rights management and two-factor authentication.

On 16 November 2020, Google announced new settings for smart features and personalization in Gmail. Under the new settings users were given control of their data in Gmail, Chat, and Meet, offering smart features like Smart Compose and Smart Reply.

On 6 April 2021, Google rolled out Google Chat and Room (early access) feature to all Gmail users.

On 28 July 2022, Google rolled out Material You to all Gmail users.

Spam filter

Gmail's spam filtering features a community-driven system: when any user marks an email as spam, this provides information to help the system identify similar future messages for all Gmail users.

Gmail Labs

The Gmail Labs feature, introduced on June 5, 2008, allows users to test new or experimental features of Gmail. Users can enable or disable Labs features selectively and provide feedback about each of them. This allows Gmail engineers to obtain user input about new features to improve them and also to assess their popularity. Popular features, like the "Undo Send" option, often "graduate" from Gmail Labs to become a formal setting in Gmail. All Labs features are experimental and are subject to termination at any time.

Gmail incorporates a search bar for searching emails. The search bar can also search contacts, files stored in Google Drive, events from Google Calendar, and Google Sites.

In May 2012, Gmail improved the search functionality to include auto-complete predictions from the user's emails.

Gmail's search functionality does not support searching for word fragments (also known as 'substring search' or partial word search). Workarounds exist.

Language support

Gmail supports multiple languages, including the Japanese interface shown here.

As of March 2015, the Gmail interface supports 72 languages, including: Arabic, Basque, Bulgarian, Catalan, Chinese (simplified), Chinese (traditional), Croatian, Czech, Danish, Dutch, English (UK), English (US), Estonian, Finnish, French, German, Greek, Gujarati, Hebrew, Hindi, Hungarian, Icelandic, Indonesian, Italian, Japanese, Kannada, Korean, Latvian, Lithuanian, Malay, Malayalam, Marathi, Norwegian (Bokmål), Odia, Persian, Polish, Punjabi, Portuguese (Brazil), Portuguese (Portugal), Romanian, Russian, Serbian, Sinhala, Slovak, Slovenian, Spanish, Swedish, Tagalog (Filipino), Tamil, Telugu, Thai, Turkish, Ukrainian, Urdu, Vietnamese, Welsh and Zulu.

Automated error messages

If you encounter an email from Mail Delivery Subsystem, it indicates that you encountered an error when trying to email someone but it is unsuccessful. This can be because of an invalid email address, timed out email, full inbox or whatever reason.

An automated email error indicating that the email has timed out.

Language input styles

In October 2012, Google added over 100 virtual keyboards, transliterations, and input method editors to Gmail, enabling users different types of input styles for different languages in an effort to help users write in languages that are not "limited by the language of your keyboard."

In October 2013, Google added handwriting input support to Gmail.

In August 2014, Gmail became the first major email provider to let users send and receive emails from addresses with accent marks and letters from outside the Latin alphabet.

Platforms

Web browsers

The modern AJAX version is officially supported in the current and previous major releases of Google Chrome, Firefox, Microsoft Edge and Safari web browsers on a rolling basis.

Gmail's "basic HTML" version works on almost all browsers. This version of Gmail has been discontinued from January 2024.

In August 2011, Google introduced Gmail Offline, an HTML5-powered app for providing access to the service while offline. Gmail Offline runs on the Google Chrome browser and can be downloaded from the Chrome Web Store.

In addition to the native apps on iOS and Android, users can access Gmail through the web browser on a mobile device.

Mobile

DeveloperGoogle
Release21 September 2010; 15 years ago
Stable release(s) [±]
Android2026.06.01 (Build 929418315) / June 9, 2026; 9 days ago
iOS6.0 (Build 260601) / June 10, 2026; 8 days ago
Wear OS2026.06.01 (Build 924674534) / June 9, 2026; 9 days ago
Operating system
Discontinued
Size~10 MB
TypeEmail client
Websitewww.gmail.com 

Gmail has native applications for iOS devices (including iPhone, iPad, and iPod Touch) and for Android devices.

In November 2014, Google introduced functionality in the Gmail Android app that enabled sending and receiving emails from non-Gmail addresses (such as Yahoo! Mail and Outlook.com) through POP or IMAP.

In November 2016, Google redesigned the Gmail app for the iOS platform, bringing the first complete visual overhaul in "nearly four years". The update added much more use of colors, sleeker transitions, and the addition of several "highly-requested" features, including Undo Send, faster search with instant results and spelling suggestions, and Swipe to Archive/Delete.

In May 2017, Google updated Gmail on Android to feature protection from phishing attacks. Media outlets noticed that the new protection was announced amid a widespread phishing attack on a combination of Gmail and Google's Docs document service that occurred on the same day.

Later in May, Google announced the addition of "Smart Reply" to Gmail on Android and iOS. "Smart Reply", a feature originally launched for Google's Inbox by Gmail service, scans a message for information and uses machine intelligence to offer three responses the user can optionally edit and send. The feature is limited to the English language at launch, with additional support for Spanish, followed by other languages arriving later.

Inbox by Gmail, another app from the Gmail team, was also available for iOS and Android devices. It was discontinued in April 2019.

Third-party programs can be used to access Gmail, using the POP or IMAP protocols. In 2019, Google rolled out dark mode for its mobile apps in Android and iOS.

Inbox by Gmail

In October 2014, Google introduced Inbox by Gmail on an invitation-only basis. Developed by the Gmail team, but serving as a "completely different type of inbox", the service is made to help users deal with the challenges of an active email. Citing issues such as distractions, difficulty in finding important information buried in messages, and receiving more emails than ever, Inbox by Gmail has several important differences from Gmail, including bundles that automatically sort emails of the same topic together, highlights that surface key information from messages, and reminders, assists, and snooze, that help the user in handling incoming emails at appropriate times.

Inbox by Gmail became publicly available in May 2015. In September 2018, Google announced it would end the service at the end of March 2019, most of its key features having been incorporated into the standard Gmail service. The service was discontinued on April 2, 2019.

Integration with Google products

In August 2010, Google released a plugin that provides integrated telephone service within Gmail's Google Chat interface. The feature initially lacked an official name, with Google referring to it as both "Google Voice in Gmail chat" and "Call Phones in Gmail". The service logged over one million calls in 24 hours. In March 2014, Google Voice was discontinued, and replaced with functionality from Google Hangouts, another communication platform from Google.

On February 9, 2010, Google commenced its new social networking tool, Google Buzz, which integrated with Gmail, allowing users to share links and media, as well as status updates. Google Buzz was discontinued in October 2011, replaced with new functionality in Google+, Google's then-new social networking platform.

Gmail was integrated with Google+ in December 2011, as part of an effort to have all Google information across one Google account, with a centralized Google+ user profile. Backlash from the move caused Google to step back and remove the requirement of a Google+ user account, keeping only a private Google account without a public-facing profile, starting in July 2015.

In May 2013, Google announced the integration between Google Wallet and Gmail, which would allow Gmail users to send money as email attachments. Although the sender must use a Gmail account, the recipient does not need to be using a Gmail address. The feature has no transaction fees, but there are limits to the amount of money that can be sent. Initially only available on the web, the feature was expanded to the Android app in March 2017, for people living in the United States.

In September 2016, Google released Google Trips, an app that, based on information from a user's Gmail messages, automatically generates travel cards. A travel card contains itinerary details, such as plane tickets and car rentals, and recommends activities, food and drinks, and attractions based on location, time, and interests. The app also has offline functionality. In April 2017, Google Trips received an update adding several significant features. The app now also scans Gmail for bus and train tickets, and allows users to manually input trip reservations. Users can send trip details to other users' email, and if the recipient also has Google Trips, the information will be automatically available in their apps as well.

Security

History

Gmail Transport Encryption by Country
Gmail transport encryption by country

Google has supported the secure HTTPS since the day it launched. In the beginning, it was only default on the login page, a reason that Google engineer Ariel Rideout stated was because HTTPS made "your mail slower". However, users could manually switch to secure HTTPS mode inside the inbox after logging in. In July 2008, Google simplified the ability to manually enable secure mode, with a toggle in the settings menu.

In 2007, Google fixed a cross-site scripting security issue that could let attackers collect information from Gmail contact lists.

In January 2010, Google began rolling out HTTPS as the default for all users.

In June 2012, a new security feature was introduced to protect users from state-sponsored attacks. A banner will appear at the top of the page that warns users of an unauthorized account compromise.

In March 2014, Google announced that an encrypted HTTPS connection would be used for the sending and receiving of all Gmail emails, and "every single email message you send or receive —100% of them —is encrypted while moving internally" through the company's systems.

Whenever possible, Gmail uses transport layer security (TLS) to automatically encrypt emails sent and received. On the web and on Android devices, users can check if a message is encrypted by checking if the message has a closed or open red padlock.

Gmail automatically scans all incoming and outgoing e-mails for viruses in email attachments. For security reasons, some file types, including executables, are not allowed to be sent in emails.

At the end of May 2017, Google announced that it had applied machine learning technology to identify emails with phishing and spam, having a 99.9% detection accuracy. The company also announced that Gmail would selectively delay some messages, approximately 0.05% of all, to perform more detailed analysis and aggregate details to improve its algorithms.

In November 2020, Google started adding click-time link protection by redirecting clicked links to Google in official Gmail clients.

Third-party encryption in transit

In Google's Transparency Report under the Safer email section, it provides information on the percentage of emails encrypted in transit between Gmail and third-party email providers.

Two-step verification

A sign-in screen on a new device, requesting user's response to a push notification sent to the user's phone

Gmail supports two-step verification, an optional additional measure for users to protect their accounts when logging in.

Once 2-Step Verification (2SV) is enabled, logging in from a new device requires an additional verification method, even after the username and password have been entered. These methods, which verify the user's identity, can include responding to a push notification on the user's Android/iOS device, entering a code generated by the Google Authenticator smartphone app, or inserting a physical security key into the computer's USB port."

Using a security key for two-step verification was made available as an option in October 2014.

24-hour lockdowns

If an algorithm detects what Google calls "abnormal usage that may indicate that your account has been compromised", the account can be automatically locked down for between one minute and 24 hours, depending on the type of activity detected. Listed reasons for a lock-down include:

  • Receiving, deleting, or downloading large amounts of mail from POP/IMAP client within a short period of time.
  • Sending a large number of messages which fail to deliver.
  • Using software which automatically logs into one's account.
  • Leaving multiple instances of Gmail open.

Anti-child pornography policy

Google combats child pornography through Gmail's servers in conjunction with the National Center for Missing & Exploited Children (NCMEC) to find children suffering abuse around the world. In collaboration with the NCMEC, Google creates a database of child pornography pictures. Each one of the images is given a unique numerical number known as a hash. Google then scans Gmail looking for the unique hashes. When suspicious images are located, Google reports the incident to the appropriate national authorities.

History

Gmail logo used until 2020
Gmail logo used until 2026

The idea for Gmail was developed by Paul Buchheit several years before it was announced to the public. The project was known by the code name Caribou. During early development, the project was kept secret from most of Google's own engineers. This changed once the project improved, and by early 2004, most employees were using it to access the company's internal email system.

Gmail was announced to the public by Google on April 1, 2004, as a limited beta release.

In November 2006, Google began offering a Java-based application of Gmail for mobile phones.

In October 2007, Google began a process of rewriting parts of the code that Gmail used, which would make the service faster and add new features, such as custom keyboard shortcuts and the ability to bookmark specific messages and email searches. Gmail also added IMAP support in October 2007. An update around January 2008 changed elements of Gmail's use of JavaScript, and resulted in the failure of a third-party script some users had been using. Google acknowledged the issue and helped users with workarounds.

Gmail exited beta status on July 7, 2009.

Prior to December 2013, users had to approve to see images in emails, which acted as a security measure. This changed in December 2013, when Google, citing improved image handling, enabled images to be visible without user approval. Images are now routed through Google's secure proxy servers rather than the original external host servers. MarketingLand noted that the change to image handling means email marketers will no longer be able to track the recipient's IP address or information about what kind of device the recipient is using. However, Wired stated that the new change means senders can track the time when an email is first opened, as the initial loading of the images requires the system to make a "callback" to the original server.

Growth

In June 2012, Google announced that Gmail had 425 million active users globally. In May 2015, Google announced that Gmail had 900 million active users, 75% of whom were using the service on mobile devices. In February 2016, Google announced that Gmail had passed 1 billion active users. In July 2017, Google announced that Gmail had passed 1.2 billion active users.

In the business sector, Quartz reported in August 2014 that, among 150 companies checked in three major categories in the United States (Fortune 50 largest companies, mid-size tech and media companies, and startup companies from the last Y Combinator incubator class), only one Fortune 50 company used Gmail – Google itself – while 60% of mid-sized companies and 92% of startup companies were using Gmail.

In May 2014, Gmail became the first app on the Google Play Store to hit one billion installations on Android devices.

Gamil Design company and misspellings

Before the introduction of Gmail, the website of product and graphic design from Gamil Design in Raleigh, North Carolina, received 3,000 hits per month. In May 2004, a Google engineer who had accidentally gone to the Gamil site a number of times contacted the company and asked if the site had experienced an increase in traffic. In fact, the site's activity had doubled. Two years later, with 600,000 hits per month, the Internet service provider wanted to charge more, and Gamil posted the message on its site "You may have arrived here by misspelling Gmail. We understand. Typing fast is not our strongest skill. But since you've typed your way here, let's share."

Google Workspace

As part of Google Workspace (formerly G Suite), Google's business-focused offering, Gmail comes with additional features, including:

  • Email addresses with the customer's domain name (@yourcompany.com)
  • 99.9% guaranteed uptime with zero scheduled downtime for maintenance
  • Either 30 GB or unlimited storage shared with Google Drive, depending on the plan
  • 24/7 phone and email support
  • Synchronization compatibility with Microsoft Outlook and other email providers
  • Support for add-ons that integrate third-party apps purchased from the Google Workspace Marketplace with Gmail

Criticism

Privacy

Google has one privacy policy that covers all of its services. Google claims that they "will not target ads based on sensitive information, such as race, religion, sexual orientation, health, or sensitive financial categories."

Automated scanning of email content

Google's mail servers automatically scan emails for multiple purposes, including filtering spam and malware, and (until 2017) adding context-sensitive advertisements next to emails.

Privacy advocates raised concerns about this practice; concerns included that allowing email content to be read by a machine (as opposed to a person) can allow Google to keep unlimited amounts of information forever; the automated background scanning of data raises the risk that the expectation of privacy in email usage will be reduced or eroded; information collected from emails could be retained by Google for years after its current relevancy to build complete profiles on users; emails sent by users from other email providers get scanned despite never having agreed to Google's privacy policy or terms of service; Google can change its privacy policy unilaterally, and for minor changes to the policy it can do so without informing users; in court cases, governments and organizations can potentially find it easier to legally monitor email communications; at any time, Google can change its current company policies to allow combining information from emails with data gathered from use of its other services; and any internal security problem on Google's systems can potentially expose many – or all – of its users.

In 2004, thirty-one privacy and civil liberties organizations wrote a letter calling upon Google to suspend its Gmail service until the privacy issues were adequately addressed. The letter also called upon Google to clarify its written information policies regarding data retention and data sharing among its business units. The organizations also voiced their concerns about Google's plan to scan the text of all incoming messages for the purposes of ad placement, noting that the scanning of confidential email for inserting third-party ad content violates the implicit trust of an email service provider.

On June 23, 2017, Google announced that, later in 2017, it would phase out the scanning of email content to generate contextual advertising, relying on personal data collected through other Google services instead. The company stated that this change was meant to clarify its practices and quell concerns among enterprise G Suite (now Google Workspace) customers who felt an ambiguous distinction between the free consumer and paid professional variants, the latter being advertising-free.

Lawsuits

In March 2011, a former Gmail user in Texas sued Google, claiming that its Gmail service violates users' privacy by scanning e-mail messages to serve relevant ads.

In July 2012, some California residents filed two class action lawsuits against Google and Yahoo!, claiming that they illegally intercept emails sent by individual non-Gmail or non-Yahoo! email users to Gmail and Yahoo! recipients without the senders' knowledge, consent or permission. A motion filed by Google's attorneys in the case concedes that Gmail users have "no expectation of privacy".

A court filing uncovered by advocacy group Consumer Watchdog in August 2013 revealed that Google stated in a court filing that no "reasonable expectation" exists among Gmail users in regard to the assured confidentiality of their emails. In response to a lawsuit filed in May 2013, Google explained:

"All users of email must necessarily expect that their emails will be subject to automated processing. Just as a sender of a letter to a business colleague cannot be surprised that the recipient's assistant opens the letter, people who use web-based email today cannot be surprised if their communications are processed by the recipient's ECS [electronic communications service] provider in the course of delivery.

A Google spokesperson stated to the media on August 15, 2013, that the corporation takes the privacy and security concerns of Gmail users "very seriously".

April 2014 Terms of service update

Google updated its terms of service for Gmail in April 2014 to create full transparency for its users in regard to the scanning of email content. The relevant revision states: "Our automated systems analyze your content (including emails) to provide you personally relevant product features, such as customized search results, tailored advertising, and spam and malware detection. This analysis occurs as the content is sent, received, and when it is stored." A Google spokesperson explained that the corporation wishes for its policies "to be simple and easy for users to understand."

In response to the update, Jim Killock, executive director of the Open Rights Group, stated: "The really dangerous things that Google is doing are things like the information held in Analytics, cookies in advertising and the profiling that it is able to do on individual accounts".

Microsoft ad campaign against Google

In 2013, Microsoft launched an advertising campaign to attack Google for scanning email messages, arguing that most consumers are not aware that Google monitors their personal messages to deliver targeted ads. Microsoft claims that its email service Outlook does not scan the contents of messages and a Microsoft spokesperson called the issue of privacy "Google's kryptonite". In response, Google stated; "We work hard to make sure that ads are safe, unobtrusive and relevant ... No humans read your e-mail or Google Account information in order to show you advertisements or related information. An automated algorithm — similar to that used for features like Priority Inbox or spam filtering — determines which ads are shown." The New York Times cites "Google supporters", who say that "Microsoft's ads are distasteful, the last resort of a company that has been unsuccessful at competing against Google on the more noble battleground of products".

Other privacy issues

2010 attack from China

In January 2010, Google detected a "highly sophisticated" cyberattack on its infrastructure that originated from China. The targets of the attack were Chinese human rights activists, but Google discovered that accounts belonging to European, American and Chinese activists for human rights in China had been "routinely accessed by third parties". Additionally, Google stated that their investigation revealed that "at least" 20 other large companies from a "wide range of businesses" - including the Internet, finance, technology, media and chemical sectors – had been similarly targeted. Google was in the process of notifying those companies and it had also worked with relevant US authorities. In light of the attacks, Google enhanced the security and architecture of its infrastructure, and advised individual users to install anti-virus and anti-spyware on their computers, update their operating systems and web browsers, and be cautious when clicking on Internet links or when sharing personal information in instant messages and emails.

Social network integration

The February 2010 launch of Google Buzz, a now defunct social network linked to Gmail, immediately drew criticism for publicly sharing details of users' contacts unless the default settings were changed. A new Gmail feature was launched in January 2014, whereby users could email people with Google+ accounts even though they do not know the email address of the recipient. Marc Rotenberg, President of the Electronic Privacy Information Center, called the feature "troubling", and compared it to the initial privacy flaw of Google Buzz's launch.

Update to DoubleClick privacy policy

In June 2016, Julia Angwin of ProPublica wrote about Google's updated privacy policy, which deleted a clause that had stated Google would not combine DoubleClick web browsing cookie information with personally identifiable information from its other services. This change has allowed Google to merge users' personally identifiable information from different Google services to create one unified ad profile for each user. After publication of the article, Google reached out to ProPublica to say that the merge would not include Gmail keywords in ad targeting.

Outages

Gmail suffered at least seven outages in 2009, causing doubts about the reliability of its service. It suffered a new outage on February 28, 2011, in which a bug caused Gmail accounts to seem empty. Google stated in a blog post that "email was never lost" and restoration was in progress. Other outages occurred on April 17, 2012, September 24, 2013, January 24, 2014, January 29, 2019  and August 20, 2020.

Google has stated that "Gmail remains more than 99.9% available to all users, and we're committed to keeping events like [the 2009 outage] notable for their rarity."

"On behalf of" tag

In May 2009, Farhad Manjoo wrote on The New York Times blog about Gmail's "on behalf of" tag. Manjoo explained: "The problems [sic] is, when you try to send outbound mail from your Gmail universal inbox, Gmail adds a tag telling your recipients that you're actually using Gmail and not your office e-mail. If your recipient is using Microsoft Outlook, he'll see a message like, 'From youroffice@domain.com on behalf of yourgmail@gmail.com.'" Manjoo further wrote that "Google explains that it adds the tag in order to prevent your e-mail from being considered spam by your recipient; the theory is that if the e-mail is honest about its origins, it shouldn't arouse suspicion by spam checking software". The following July, Google announced a new option that would remove the "On behalf of" tag, by sending the email from the server of the other email address instead of using Gmail's servers.

Thursday, June 18, 2026

Mass psychogenic illness

From Wikipedia, the free encyclopedia
Mass psychogenic illness
Other names

Mass hysteria, epidemic hysteria, mass sociogenic illness

 

Painting by Pieter Brueghel the Younger of dancing peasants
Dancing plagues of the Middle Ages are thought to have been caused by mass hysteria. (Painting by Pieter Brueghel the Younger)
SpecialtyPsychiatry, clinical psychology
SymptomsHeadache, dizziness, nausea, abdominal pain, cough, fatigue, sore throat
DurationFor most cases, under 12 hours to days
Risk factorsChildhood or adolescence; female sex (girls/women); intense media coverage, or widespread publicity
Differential diagnosisActual diseases (e.g., infectious diseases, environmental toxins or exposures), somatic symptom disorder
TreatmentUsually isolation or separation from perceived threat
PrognosisMost recover

Mass psychogenic illness (MPI), also called mass sociogenic illness, mass psychogenic disorder, epidemic hysteria or mass hysteria, involves the spread of illness symptoms through a population where there is no infectious agent responsible for contagion. It is the rapid spread of illness signs and symptoms affecting members of a cohesive group, originating from a nervous system disturbance involving excitation, loss, or alteration of function, whereby physical complaints that are exhibited unconsciously have no corresponding organic causes that are known.

Signs and symptoms

Timothy F. Jones of the Tennessee Department of Health compiled the following symptoms based on their commonality in outbreaks occurring in 1980–1990:

Predominant symptoms in nine outbreaks of mass psychogenic illness
Symptom Patients

reporting (%)

Headache 67
Dizziness or light-headedness 46
Nausea 41
Abdominal cramps or pain 39
Cough 31
Fatigue, drowsiness or weakness 31
Sore or burning throat 30
Hyperventilation or difficulty breathing 19
Watery or irritated eyes 13
Chest tightness/chest pain 12
Inability to concentrate/trouble thinking 11
Vomiting 10
Tingling, numbness or paralysis 10
Anxiety or nervousness 8
Diarrhea 7
Trouble with vision 7
Rash 4
Loss of consciousness/syncope 4
Itching 3

Causes and risk factors

MPI is distinct from other types of collective or mass delusions by involving physical symptoms.Qualities of MPI outbreaks often include:

  • symptoms that have no plausible organic basis;
  • symptoms that are transient and benign;
  • symptoms with rapid onset and recovery;
  • occurrence in a segregated group;
  • the presence of extraordinary anxiety;
  • symptoms that are spread via sight, sound or oral communication;
  • a spread that moves down the age scale, beginning with older or higher-status people;

British psychiatrist Simon Wessely distinguishes between two forms of MPI:

  • Mass anxiety hysteria: "consists of episodes of acute anxiety, occurring mainly in schoolchildren. Prior tension is absent and the rapid spread is by visual contact."
  • Mass motor hysteria: "consists of abnormalities in motor behaviour. It occurs in any age group and prior tension is present. Initial cases can be identified and the spread is gradual. ... [T]he outbreak may be prolonged."

While his definition is sometimes adhered to, others contest Wessely's definition and describe outbreaks with qualities of both mass motor hysteria and mass anxiety hysteria.

The DSM-IV-TR does not define a diagnosis for this condition but the text describing conversion disorder states that "In 'epidemic hysteria', shared symptoms develop in a circumscribed group of people following 'exposure' to a common precipitant."

Prevalence and intensity

Cases of MPI frequently involve adolescents and children as the primary affected groups, with females often being disproportionately impacted. The hypothesis that those prone to extraversion or neuroticism, or those with low IQ scores, are more likely to be affected in an outbreak of hysterical epidemic has not been consistently supported by research. Bartholomew and Wessely state that it "seems clear that there is no particular predisposition to mass sociogenic illness and it is a behavioural reaction that anyone can show in the right circumstances."

Intense media coverage seems to exacerbate outbreaks. The illness may also recur after the initial outbreak. John Waller advises that once it is determined that the illness is psychogenic, it should not be given credence by authorities. For example, in the Singapore factory case study, calling in a medicine man to perform an exorcism seemed to perpetuate the outbreak.

History

Medieval period

The earliest studied cases linked with epidemic hysteria are the dancing manias of the Middle Ages, including St. John's dance and tarantism. These were supposed to be associated with spirit possession or the bite of the tarantula. Those with dancing mania would dance in large groups, sometimes for weeks at a time. The dancing was sometimes accompanied by stripping, howling, the making of obscene gestures, or reportedly laughing or crying to the point of death. Dancing mania was widespread over Europe.

Between the 15th and 19th centuries, instances of motor hysteria were common in nunneries. The young women that made up these convents were sometimes forced there by family. Once accepted, they took vows of chastity and poverty. Their lives were highly regimented and often marked by strict disciplinary action. The nuns would exhibit a variety of behaviors, usually attributed to demonic possession. They would often use crude language and exhibit suggestive behaviors.

In the English translation of Hecker's The Epidemics of the Middle Ages (1844), the translator and 18th century epidemiologist Benjamin Guy Babington included a personal note of his in the Hysteria section of The Dancing Mania chapter. Babington's note recalled reading an uncited French medical journal that described a large convent of nuns in France that collectively began to meow like cats one day. The nuns meowed for long periods of time throughout the day, for several hours, until they were beaten with rods to cease the excessive meowing.

Priests were often called in to exorcise demons.

In factories

MPI outbreaks occurred in factories following the industrial revolution (1760–1840) in England, France, Germany, Italy, Russia, the United States and Singapore.

W. H. Phoon, Ministry of Labour in Singapore, gives a case study of six outbreaks of MPI in Singapore factories between 1973 and 1978. They were characterized by (1) hysterical seizures of screaming and general violence, wherein tranquilizers were ineffective (2) trance states, where a worker would claim to be speaking under the influence of a spirit or jinn and (3) frightened spells: some workers complained of unprecedented fear, or of being cold, numb, or dizzy. Outbreaks would subside in about a week. Often a bomoh (medicine man) would be called in to do a ritual exorcism. This technique was not effective and sometimes seemed to exacerbate the MPI outbreak. Females and Malay people were affected disproportionately.

Especially notable is the "June Bug" outbreak: In June 1962, a peak month in factory production, 62 workers at a dressmaking factory in a textile town in the Southern United States experienced symptoms including severe nausea and breaking out on the skin. Most outbreaks occurred during the first shift, where four fifths of the workers were female. Of 62 total outbreaks, 59 were women, some of whom believed they were bitten by bugs from a fabric shipment. Entomologists and others were called in to discover the pathogen, but none was found.

Kerchoff coordinated the interview of affected and unaffected workers at the factory, and summarized his findings:

  • Strain – those affected were more likely to work overtime frequently and provided the majority of the family income. Many were married with children.
  • Affected persons tended to deny their difficulties. Kerchoff postulates that such were "less likely to cope successfully under conditions of strain."
  • Results seemed consistent with a model of social contagion. Groups of affected persons tended to have strong social ties.

Kerchoff linked the rapid rate of contagion with the apparent reasonableness of the bug infestation theory and the credence given to it in accompanying news stories.

In 1974, Stahl and Lebedun described an outbreak of mass sociogenic illness in the data center of a university town in the United States Midwest. Ten of 39 workers smelling an unconfirmed "mystery gas" were rushed to a hospital with symptoms of dizziness, fainting, nausea and vomiting. They reported that most workers were young women, either putting their husbands through school or supplementing the family income. Those affected were found to have high levels of job dissatisfaction. Those with strong social ties tended to have similar reactions to the supposed gas, which only one unaffected woman reported smelling. No gas was detected in tests of the data center.

In schools

In 1962, the Tanganyika laughter epidemic was an outbreak of laughing attacks, rumored to have occurred in or near the village of Kanshasa on the western coast of Lake Victoria in what is now Tanzania, eventually affecting 14 different schools and over 1,000 people.

On the morning of Thursday 7 October 1965, at a girls' school in Blackburn in England, several girls complained of dizziness. Some fainted. Within a couple of hours, 85 girls from the school were rushed by ambulance to a nearby hospital after fainting. Symptoms included swooning, moaning, chattering of teeth, hyperpnea, and tetany. Moss and McEvedy published their analysis of the event about one year later. Their conclusions follow. Their conclusion about the above-average extraversion and neuroticism of those affected is not necessarily typical of MPI:

  • Clinical and laboratory findings were essentially negative.
  • Investigations by the public health authorities did not uncover any evidence of pollution of food or air.
  • The epidemiology of the outbreak was investigated by means of questionnaires administered to the whole school population. It was established that the outbreaks began among the 14-year-olds, but that the heaviest incidence moved to the youngest age groups.
  • By using the Eysenck Personality Inventory, it was established that, in all age groups, the mean E [extraversion] and N [neuroticism] scores of the affected were higher than those of the unaffected.
  • The younger girls proved more susceptible, but disturbance was more severe and lasted longer in the older girls.
  • It was considered that the epidemic was hysterical, that a previous polio epidemic had rendered the population emotionally vulnerable, and that a three-hour parade, producing 20 faints on the day before the first outbreak, had been the specific trigger.
  • The data collected were thought to be incompatible with organic theories and with the compromise theory of an organic nucleus.

In 1974, mass hysteria affected schools in Berry, Alabama, and Miami Beach. In Berry, it took the form of recurring itches. In the episode in Miami Beach initially triggering fears of poison gas. It was traced back to a popular student who happened to be sick with a virus.

In June 1990, thousands were affected by the spread of a supposed illness in a province of Kosovo in March to June 1990, exclusively affecting ethnic Albanians, most of whom were young adolescents. Symptoms included headaches, dizziness, impeded respiration, muscle weakness, burning sensations, cramps, retrosternal/chest pain, dry mouth and nausea. After the illness had subsided, a bipartisan Federal Commission released a document, offering the explanation of psychogenic illness. Radovanovic of the Department of Community Medicine and Behavioural Sciences Faculty of Medicine in Safat, Kuwait, reported:

This document did not satisfy either of the two ethnic groups. Many Albanian doctors believed that what they had witnessed was an unusual epidemic of poisoning. The majority of their Serbian colleagues also ignored any explanation in terms of psychopathology. They suggested that the incident was faked with the intention of showing Serbs in a bad light but that it failed due to poor organization.

Radovanovic stated that this reported instance of mass sociogenic illness was precipitated by the demonstrated volatile and culturally tense situation in the province.

Another possible case occurred in Belgium in June 1999 when people, mainly schoolchildren, became ill after drinking Coca-Cola. In the end, scientists were divided over the scale of the outbreak, whether it fully explains the many different symptoms and the scale to which sociogenic illness affected those involved.

Starting around 2009, a spate of apparent poisonings at girls' schools across Afghanistan began to be reported; symptoms included dizziness, fainting and vomiting. The United Nations, World Health Organization and NATO's International Security Assistance Force carried out investigations of the incidents over multiple years, but never found any evidence of toxins or poisoning in the hundreds of blood, urine and water samples they tested. The conclusion of the investigators was that the girls were experiencing a mass psychogenic illness.

In 2011, a possible outbreak of mass psychogenic illness occurred at Le Roy Junior-Senior High School, in Le Roy, New York, in which multiple students began having symptoms similar to Tourette syndrome. Various health professionals ruled out such factors as Gardasil, drinking water contamination, illegal drugs, carbon monoxide poisoning and various other potential environmental or infectious causes, before diagnosing the students with a conversion disorder and mass psychogenic illness.

In August 2019 the BBC reported that schoolgirls at the Ketereh national secondary school (SMK Ketereh) in Kelantan, Malaysia, started screaming, with some claiming to have seen 'a face of pure evil'. Simon Wessely of King's College Hospital, London, suggested it was a form of 'collective behaviour'. Robert Bartholomew, an American medical sociologist and author, said, "It is no coincidence that Kelantan, the most religiously conservative of all Malaysian states, is also the one most prone to outbreaks." This view is supported by Afiq Noor, an academic, who argues that the stricter implementation of Islamic law in school in states such as Kelantan is linked to the outbreaks. He suggested that the screaming outbreak was caused by the constricted environment. In Malaysian culture, burial sites and trees are common settings for supernatural tales about the spirits of dead infants (toyol), vampiric ghosts (pontianak) and vengeful female spirits (penanggalan). Authorities responded to the Kelantan outbreak by cutting down trees around the school.

Outbreaks of mass psychogenic illness "have been reported in Catholic convents and monasteries across Mexico, Italy and France, in schools in Kosovo and even among cheerleaders in a rural North Carolina town".

Episodes of mass hysteria have been frequent in Nepalese schools, at times even leading to the temporary closure of those schools involved. In 2018, a unique phenomenon of "recurrent epidemic of mass hysteria" was reported from a school of Pyuthan district of western Nepal after a nine-year-old school girl developed crying and shouting episodes. Other children of the same school became affected in rapid succession, resulting in 47 affected students, 37 females, 10 males, in the same day. Since 2016, similar episodes of mass psychogenic illness have been occurring every year at the same school. This is seen as a rather atypical case of recurrent mass hysteria.

In July 2022, reports of up to 15 girls showing unusual symptoms such as screaming, trembling, and banging their heads came up from a government school in Bageshwar, Uttarakhand, India. Mass psychological illness has been suggested as a possible cause.

In late 2022 and early 2023, thousands of students, mostly girls, in numerous schools in Iran were initially believed to have been poisoned in various and undetermined manners by unidentified perpetrators and numerous arrests were made. On 29 April 2023, the Iranian Intelligence Ministry released the findings of a comprehensive investigation which concluded that the reported illnesses were not caused by any toxic substances. Instead they were suggested to have been due to a variety of reasons, including exposure to a variety of non-toxic substances, mass hysteria, and malingering.

In October 2023, over 100 students from the St. Theresa's Eregi Girls' High School in Musoli, Kenya were hospitalized due to rapid and involuntary arm and leg movement, sometimes accompanied by headaches and vertigo. Routine medical tests revealed nothing unusual, and there were no signs of infectious disease as a cause. Ultimately it was decided that the events were caused by "stress due to upcoming exams" and the incident was determined to be an incident of "hysteria".

Due to the determination of collective stress as the cause, medical sociologist Robert Bartholomew favors the neutral term mass psychogenic illness over mass hysteria, as people respond more favorably to a diagnosis of stress induced symptoms than to a diagnosis of mass hysteria. Bartholomew notes such outbreaks are not unusual in schools in the developing world. This is particularly true in schools in which discipline is tight and accompanied with cultural strain between administrators and students. An outbreak can be preceded by months of such tension, which then results in physical symptoms such as seen in Musoli. Far from faking it, "Under such prolonged stress, the nerves and neurons that send messages to the brain become disrupted, resulting in an array of neurological symptoms such as twitching, shaking, convulsions, and trance-like states."

Bartholomew observes that school-stress borne illness such as occurred here have not been uncommon in Africa since the 1960s. Some appear to be due to Christian missionary schools largely ignoring local traditions and mythologies. Instead, such schools impart their own mythologies and culture. This may create overwhelming anxiety due to the students being taught one thing at home, such as ancestor worship, which is then forbidden at a Christian mythology based school.

Other such outbreaks have similar tradition-based causes, such as a 1995 outbreak of "bouts of screaming, crying, foaming at the mouth, and partial paralysis" in over 600 girls at an African Muslim school in Northern Nigeria. This outbreak was surmised to be due to expectations of traditional arranged marriage, colliding with modernity's emphasis on romantic love that the students had observed in movies. The difference between these two cases of mass psychogenic illness reinforces that each outbreak needs to be evaluated in the specific circumstances in which it occurred, as such instances are "never spontaneous reactions to stress per se; they are always couched in some unique context."

The 1997 Pokémon incident

On December 16, 1997, the Pokémon anime episode "Dennō Senshi Porygon" (Electric Soldier Porygon) aired on TV Tokyo in Japan at 6:30 PM Japan Standard Time. The episode was watched by approximately 4.6 million households. Twenty minutes into the episode, a scene featured Pikachu using an electrical attack on missiles, resulting in an explosion with rapidly alternating red and blue strobe lights that flashed at approximately 12 Hz for about six seconds, using an anime technique called paka paka.

Japan's Fire Defense Agency reported that 685 children, 310 boys and 375 girls, were taken to hospitals by ambulances, with complaints of blurred vision, headaches, dizziness, nausea, seizures, convulsions, and loss of consciousness. More than 150 were admitted to hospitals, and two remained hospitalized for more than two weeks. The incident, dubbed "Pokémon Shock" (ポケモンショック, Pokémon Shokku) by the Japanese press, resulted in immediate action by authorities. TV Tokyo issued a public apology the following day and suspended the program. Nintendo shares fell nearly 3.2% as news of the incident spread. The Pokémon anime went into a four-month hiatus before returning in April 1998 with significant changes to prevent similar incidents.

While initial reports suggested thousands of children were affected, research by Benjamin Radford and sociologist Robert Bartholomew revealed a more complex picture. Their study, published in the Southern Medical Journal in 2001, found that while some children experienced genuine photosensitive epilepsy seizures, the vast majority of the over 12,000 children who reported symptoms exhibited signs more consistent with mass psychogenic illness. The study noted that many of the reported symptoms such as headaches, dizziness, and nausea were more typical of mass hysteria than of epileptic seizures, and that symptoms typically associated with seizures (drooling, stiffness, tongue biting) were largely absent.

Crucially, the researchers discovered that the timeline of the outbreak did not match what would be expected from photosensitive epilepsy alone. While approximately 600-700 children were affected on the evening of the broadcast, the number of reported cases increased dramatically, by more than 10,000, only after extensive media coverage the following day and discussions among schoolchildren. Some viewers even experienced symptoms while watching news reports that rebroadcast clips of the scene. The characteristic features of the episode were found to be consistent with epidemic hysteria, triggered by sudden anxiety after dramatic mass media reports describing the initial genuine photosensitive-epilepsy seizures.

The incident led to significant changes in Japanese broadcasting standards. New guidelines were implemented including: flashing images should not flicker faster than three times per second for red content or five times per second for other colors; flashing images should not be displayed for more than two seconds total; and stripes, whirls and concentric circles should not take up large portions of the screen. A warning about viewing distance and room lighting was added to the beginning of all Japanese television anime shows. The episode "Dennō Senshi Porygon" has never been rebroadcast anywhere in the world and was removed from rotation. The incident holds the Guinness World Record for "Most Photosensitive Epileptic Seizures Caused by a Television Show".

The Pokémon incident demonstrates how mass psychogenic illness can occur alongside genuine medical events. The initial physical stimulus of the strobe effect causing real seizures in photosensitive individuals triggered a broader wave of psychogenic symptoms through social contagion, amplified by extensive media coverage and public panic. Radford and Bartholomew concluded that while the episode genuinely caused photosensitive-epilepsy seizures in several hundred susceptible children, the majority of the more than 12,000 reported cases represented an outbreak of mass sociogenic illness as one of the largest and best-documented such outbreaks in modern times.

Terrorism and biological warfare

In 2002, Bartholomew and Wessely stated that the "concern that after a chemical, biological or nuclear attack, [is that] public health facilities may be rapidly overwhelmed by the anxious and not just the medical and psychological casualties." Early symptoms of those affected by MPI are difficult to differentiate from those actually exposed to the dangerous agent.

The first Iraqi missile hitting Israel during the Persian Gulf War was believed to contain chemical or biological weapons. Though this was not the case, 40% of those in the vicinity of the blast reported breathing problems.

Following the 2001 anthrax attacks in October 2001, there were over 2,300 false anthrax alarms in the United States. Some reported physical symptoms of what they believed to be anthrax.

In 2001, a man sprayed what was later found to be a window cleaner into a subway station in Maryland. Thirty-five people were treated for nausea, headaches and sore throats.

Havana syndrome

Beginning in 2016, some staff stationed at the US embassy in Cuba reported medical symptoms that initially were attributed to "sonic attacks", and later to other unknown weaponry. The symptoms were dubbed "Havana syndrome" by the media. The following year, some US government employees in China reported similar symptoms. Eventually, similar reports came from US government employees and their families around the globe, including in Washington DC. Due to lack of evidence of actual attack and other factors, some scientists suggested the alleged symptoms were psychogenic in nature.

Seven U.S. intelligence agencies headed by the CIA spent years reviewing thousands of possible cases of Havana syndrome and preparing a report. On 1 March 2023, the House Intelligence Committee released an unclassified version of the report, titled an "Intelligence Community Assessment". Politico summarized the results by saying, "The finding undercuts a years-long narrative, propped up by more than a thousand reports from government employees, that a foreign adversary used pulsed electro-magnetic energy waves to sicken Americans."

A 2023 academic review article stated that the U.S. intelligence community had concluded that Havana Syndrome is "a socially constructed catch-all category for an array of pre-existing health conditions, responses to environmental factors, and stress reactions that were lumped under a single label".

Children in recent refugee families

Refugee children in Sweden have been reported to fall into coma-like states on learning their families will be deported. The condition, known as resignation syndrome (Swedish: uppgivenhetssyndrom), is believed to only exist among the refugee population in Sweden, where it has been prevalent since the early part of the 21st century. Commentators state "a degree of psychological contagion" is inherent to the condition, by which young friends and relatives of the affected individual can also come to have the condition.

In a 130-page report on the condition, commissioned by the government and published in 2006, a team of psychologists, political scientists and sociologists hypothesized that it was a culture-bound syndrome, a psychological illness endemic to a specific society.

This phenomenon has later been called into question, with children witnessing that they were forced, by their parents, to act in a certain way in order to increase chances of being granted residence permits. As evidenced by medical records, healthcare professionals were aware of this scam, and witnessed parents who actively refused aid for their children, but remained silent. Later, Sveriges Television, Sweden's national public television broadcaster, were severely critiqued by investigative journalist Janne Josefsson for failing to uncover the truth.

Society and culture

Social media

After the rise of a popular breakthrough YouTube channel in 2019, where the presenter exhibits extensive Tourette's-like behavior, there was a sharp rise in young people referred to clinics specializing in tics, thought to be related to social contagion spread via the Internet, and also to stress from eco-anxiety and the COVID-19 pandemic.

A report published in August 2021 found evidence that social media was the primary vector for transmission of the Tourette's-like behavior and that it predominantly affects adolescent girls, declaring the phenomenon the first recorded instance of mass social media–induced illness (MSMI).

Research

Diagnostic challenges

Besides the difficulties common to all research involving the social sciences, including a lack of opportunity for controlled experiments, MSI or MPI presents special difficulties to researchers in this field. Balaratnasingam and Janca report that the methods for "diagnosis of mass hysteria remain contentious." According to Jones, the effects resulting from MPI "can be difficult to differentiate from [those of] bioterrorism, rapidly spreading infection or acute toxic exposure."

These troubles result from the residual diagnosis of MPI. There is a lack of logic in an argument that proceeds: "There isn't anything, so it must be MPI." It is an example of an argument from ignorance, with ignorance here intended to mean "an absence of contrary evidence". It precludes the notion that an organic factor could have been overlooked (i.e. that there may have been insufficient investigation), or the possibility that the answer may currently be unknown but known at a future point in time. Nevertheless, running an extensive number of tests extends the probability of false positives. Singer, of the Uniformed Schools of Medicine, has summarized the problems with such a diagnosis:

[Y]ou find a group of people getting sick, you investigate, you measure everything you can measure ... and when you still can't find any physical reason, you say "well, there's nothing else here, so let's call it a case of MPI."

Relationship to autism and mirror neurons

Due to the role of the visual and auditory systems in MPI, a link between MPI and mirror neurons has been suggested. In this context, MPI appears as the neurological opposite of autism, caused by an overactive, not underactive, mirror neuron system. This could explain the gender difference bias observed in these two conditions, with autism predominantly affecting males (persons with autism show diminished activity in the mirror neuron system), and MPI predominantly affecting young girls, who appear to have a more sensitive mirror system.

Recovered-memory therapy

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