Manual:$wgEnotifUseJobQ

Email notification (Enotif) settings: $wgEnotifUseJobQ
Send mails via the job queue.
Introduced in version:1.11.0 (r21898)
Removed in version:1.27.0 (Gerrit change 265682; git #334e8f8f)
Allowed values:(boolean)
Default value:false

Details edit

Since MediaWiki 1.27, the job queue is always used to send email.

If true, send mails via the job queue.

If you are setting this value to true, check that $wgServer is set explicitly in your LocalSettings.php , as the usual $_SERVER method for detecting the wiki URL will not work if the job queue is run from a cron script.