--- UserMailer.php.orig	2006-05-12 19:56:40.087049192 +0200
+++ UserMailer.php	2006-05-12 19:57:14.558808688 +0200
@@ -94,7 +94,7 @@
 		$wgErrorString = '';
 		set_error_handler( 'mailErrorHandler' );
 		wfDebug( "Sending mail via internal mail() function\n" );
-		mail( $to, $subject, $body, $headers );
+		mail( $to, $subject, $body, $headers, "-f $from" );
 		restore_error_handler();
 
 		if ( $wgErrorString ) {