Manual:$wgSMTP

Details
To send emails (email confirmations, notifications, ), you should use a third party email provider and allow MediaWiki to send email with it through SMTP. The settings are stored as an array in $wgSMTP. Set to false (the default value) to use the built-in PHP function, but do note that if you do so your emails will most likely end up in the user's spam folder.

Also configure  and make sure  matches the sending email address.

$wgSMTP is configured like so:

is a MediaWiki-specific setting used to build the Message-ID email header (see [ http://www.faqs.org/rfcs/rfc2822.html RFC 2822, sec 3.6.4] for more information on a properly formatted Message-ID). If not provided, will default to . For the remaining settings, see Mail::factory for a more complete description. (Scroll down to the parameter.)

Error sending mail: Unknown error in PHP's mail function MediaWiki
Be sure that  and  are set correctly, and match your email address. Some hosts will reject to send an email with a sender that doesn't match the account that sends the email.

If your server has  enabled, be sure to configure it correctly to enable sending mails from the webserver.

Error sending mail: authentication failure SMTP: STARTTLS
PEAR's mail will try to use TLS when connecting to the mail server if the server supports it, even if you don't specify ssl:// in the host. But if the server certificate is not valid (CA not trusted, certificate has expired, CN does not match server name/IP address, etc.) it will refuse to work, and instead you'll get the following error:

authentication failure [SMTP: STARTTLS failed (code: 220, response: begin TLS negotiation)]

You must fix the certificate issues for mail to work.

Timeout issues
If the incorrect port is used, email will timeout without returning an error, and the website will appear unresponsive to the user. Consult your email provider's manual or try the other common SMTP ports: 25, 465, and 587.

By default, Amazon EC2 throttles traffic on SMTP port 25 for all instances. If you continue to receive timeout errors using SMTP port 25, you can request that the throttle be removed or you can change the port that is used for sending (for example, 587). For more information, see [ https://aws.amazon.com/premiumsupport/knowledge-center/smtp-connectivity-timeout-issues-ses/?nc1=h_ls How do I troubleshoot SMTP connectivity or timeout issues with Amazon SES?]
 * Timeout issues with AWS SES

require_once: Failed opening required Net/Socket.php
Check your LocalSettings.php for any lines that call. These should not be needed but can mess up SMTP support. Remove them from LocalSettings.php if present.

Mailserver does not accept sender (From)
If you are not able to send any email because your mailserver says something like "you are not authorized to use this sender" (or something like that), first check if your "SMTP username" is consistent with your email sender (see ) then, if you have an old wiki, see.

If you don't solve it, contact your mailserver.