I've got a little old server with CentOS 6.5 on it. The hardware is old and crappy, but enough for what it has to do. Which consists of SSH (+SFTP), Apache, PHP and MySQL.

Still, I'm trying to cut away all that I can. One thing that it does not need to do is to be an SMTP server. There are no mailboxes on it and nobody will ever route mail through it. However I do want it to send me an email when something goes wrong. Also, the webpages will send emails from PHP.

So that brings me to the question - can I set up the mail system in such a way that there isn't an expensive mailer daemon sitting in the background with queues and whatnotelse, but rather every email is directly and immediately delivered to an external SMTP server? And how do I go about it?