Manual:$wgEnotifFromEditor

Details
If true, sets the From: address of e-mail notification from the Page editor e-mail address, otherwise, the e-mail notification appears to be sent from the wiki server administration address ($wgEmergencyContact).

If the user has not opted-in to e-mail notification then $wgEmergencyContact will be used.

If $wgEmailAuthentication is false, this setting is ignored.