Index: wp-includes/pluggable-functions.php
===================================================================
--- wp-includes/pluggable-functions.php	(revision 1620)
+++ wp-includes/pluggable-functions.php	(working copy)
@@ -112,11 +112,17 @@
 }
 endif;
 
+if ( !function_exists('wp_default_mailfrom') ) :
+function wp_default_mailfrom() {
+	return get_settings('admin_email');
+}
+endif;
+
 if ( !function_exists('wp_mail') ) :
 function wp_mail($to, $subject, $message, $headers = '') {
 	if( $headers == '' ) {
 		$headers = "MIME-Version: 1.0\n" .
-			"From: wordpress@" . preg_replace('#^www\.#', '', strtolower($_SERVER['SERVER_NAME'])) . "\n" . 
+			"From: " . wp_default_mailfrom() . "\n" . 
 			"Content-Type: text/plain; charset=\"" . get_settings('blog_charset') . "\"\n";
 	}
 
@@ -280,7 +286,7 @@
 	$notify_message .= get_permalink($comment->comment_post_ID) . "#comments\r\n\r\n";
 	$notify_message .= sprintf( __('To delete this comment, visit: %s'), get_settings('siteurl').'/wp-admin/post.php?action=confirmdeletecomment&p='.$comment->comment_post_ID."&comment=$comment_id" ) . "\r\n";
 
-	$wp_email = 'wordpress@' . preg_replace('#^www\.#', '', strtolower($_SERVER['SERVER_NAME']));
+	$wp_email = wp_default_mailfrom();
 
 	if ( '' == $comment->comment_author ) {
 		$from = "From: \"$blogname\" <$wp_email>";
Index: wp-content/plugins/wp-db-backup.php
===================================================================
--- wp-content/plugins/wp-db-backup.php	(revision 1620)
+++ wp-content/plugins/wp-db-backup.php	(working copy)
@@ -639,7 +639,7 @@
 			$data = chunk_split(base64_encode($file));
 			$headers = "MIME-Version: 1.0\n";
 			$headers .= "Content-Type: multipart/mixed; boundary=\"$boundary\"\n";
-			$headers .= 'From: ' . get_settings('admin_email') . "\n";
+			$headers .= 'From: ' . wp_default_mailfrom() . "\n";
 		
 			$message = sprintf(__("Attached to this email is\n   %1s\n   Size:%2s kilobytes\n"), $filename, round(filesize($diskfile)/1024));
 			// Add a multipart boundary above the plain message
Index: wp-admin/install.php
===================================================================
--- wp-admin/install.php	(revision 1620)
+++ wp-admin/install.php	(working copy)
@@ -182,7 +182,7 @@
 $admin_caps = serialize(array('administrator' => true));
 $wpdb->query("INSERT INTO $wpdb->usermeta (user_id, meta_key, meta_value) VALUES ({$wpdb->insert_id}, '{$table_prefix}capabilities', '{$admin_caps}');");
 
-$message_headers = 'From: ' . $weblog_title . ' <wordpress@' . $_SERVER['SERVER_NAME'] . '>';
+$message_headers = 'From: ' . $weblog_title . ' <' . wp_default_mailfrom() . '>';
 $message = sprintf(__("Your new WordPress blog has been successfully set up at:
 
 %1\$s