diff --git a/lib/os/class.ISPConfigDebianOS.inc.php b/lib/os/class.ISPConfigDebianOS.inc.php
index e5c8a5a97ad69c42f5e757c7a41bdf9043e1b899..9cfc57b9a9b684ee4c692506070633db56ca926e 100644
--- a/lib/os/class.ISPConfigDebianOS.inc.php
+++ b/lib/os/class.ISPConfigDebianOS.inc.php
@@ -1078,6 +1078,7 @@ mailman-unsubscribe:  "|/var/lib/mailman/mail/mailman unsubscribe mailman"';
 			$replacements = array(
 				'/^\s*\$config\s*\[["\']default_host["\']\]\s*=.*$/m' => '$config[\'default_host\'] = \'localhost\';',
 				'/^\s*\$config\s*\[["\']smtp_server["\']\]\s*=.*$/m' => '$config[\'smtp_server\'] = \'%h\';',
+				'/^\s*\$config\s*\[["\']smtp_port["\']\]\s*=.*$/m' => '$config[\'smtp_port\'] = 25;',
 				'/^\s*\$config\s*\[["\']smtp_user["\']\]\s*=.*$/m' => '$config[\'smtp_user\'] = \'%u\';',
 				'/^\s*\$config\s*\[["\']smtp_pass["\']\]\s*=.*$/m' => '$config[\'smtp_pass\'] = \'%p\';'
 			);