Setting up any system analyzer, we want to always keep a track on all events happened in our machines. The best way to make that – email alerts. It means every time when application gets alert, it’s going to forward the copy of it to your email.
By default applications like OSSEC supports only local mail servers. But what if we just don’t have them? What if we use only tools like Gmail, Yahoo etc.? At that rate we could build mail relay listening on 25 port for applications work.