Mail server solution, to create a custom ticketing system

I need an incoming and outgoing mail solution that is stable and reliable and doesn’t take too much resources.

For the outgoing mail, I want to be able to send from multiple domains (through php cron) with DKIM signature and all other email standards to make sure my recipients will receive the messages and my domain will stay off the black lists.

While for the incoming messages, I would like to have a lot of aliases. And if possible tinker with the code. Ideally id like to be able to check new messages with cron and add them to a DB. What I’d also like is to be able to send canned replied upon receiving a message. So something like a ticketing system.

I’ve seen a bunch of different tutorials on here for Ubuntu 14.04, but I am not sure which mail server will allow me to do this.

Can i get any recommendations that will enable me to do at least some of the things I mentioned above?

Thanks