Email notification is a feature of the MediaWiki software on which Wikipedia runs. It allows editors who have registered an account and provided an email address to receive automatic email notifications when their user talk page or other watchlisted page is changed.
The feature is activated on the English-language version of Wikipedia (since May 2011 for the user talk and April 2012 for the watchlist) and can be set in the Email options part of the User Profile section of your user preferences.
The template {{Email user notification}}
signals that you have email notification enabled. It produces the icon at the top right of this page.
Video Help:Email notification
Talk page
Email notification is enabled by default for messages left on your talk page, when you are mentioned or thanked, when someone links to or reviews a page you created, and when someone changes your user rights. Emails are sent from wiki@wikimedia.org.
Once an email notification has been sent, additional talk-page changes will not result in further notifications, until you have logged in and visited your talk page. Your own page changes do not trigger an email notification.
Maps Help:Email notification
Watched pages
If your Preferences has "Email me when a page or file on my watchlist is changed" set, then only by visiting a page will you actually set its email notification flag.
Once you miss the email for a particular page change or don't visit the page (or ignore the email), you will not receive any more emails for that page. You can still dutifully monitor that page by its watchlist edit-summaries, but its particular email notification flag will remain unset until you visit it. This facilitates monitoring a large watchlist while preventing potentially useless emails to you.
In case you want to set all email notifications anyway, you can at any time mark all pages "visited". If your Preferences -> Gadgets has "Display pages on your watchlist that have changed since your last visit in bold", then your watchlist will have a button labeled "Mark all pages visited". That button will effectively set all of your email notification flags.
Technical notes
Source of article : Wikipedia