Manual:$wgEnotifRevealEditorAddress

Details
If true, sets the Reply-To: field of an e-mail notification to the e-mail address of the user who made the edit. Allows e-mail notification recipients to quickly reply to the editor of a watched page. Set to false to suppress the page editor's address in e-mail notifications.

To have the user's email address appear in the From: field instead of just Reply-To:, set $wgEnotifFromEditor.

If $wgEmailAuthentication is false, this setting is ignored.