Manual:$wgEnotifFromEditor

Details
If true, sets the From: address of e-mail notification as the e-mail address of the user who made the edit. Otherwise, the e-mail notification appears to be sent from the wiki server administration address ($wgPasswordSender).

If the user who made the edit has not provided an e-mail address, or has not allowed their address to be disclosed, the e-mail will appear to come from $wgPasswordSender.

You need to set $wgEnotifRevealEditorAddress to true for this setting to take effect.

If $wgEmailAuthentication is false, this setting is ignored.