Added it but I still get error:
Warning: file_exists() [function.file-exists]: open_basedir restriction in effect. File(config/config.php) is not within the allowed path(s): (/usr/share/squirrelmail:/var/www/clients/client1/web3/web:/var/www/clients/client1/web3/tmp:/var/www/mydomain.com/web:/srv/www/mydomain.com/web:/usr/share/php5:/tmp:/usr/share/phpmyadmin) in /usr/share/squirrelmail/index.php on line 15
ERROR: Config file "config/config.php" not found. You need to configure SquirrelMail before you can use it.
Strange that it came up out of nothing and no other domains have this issue?