Track my VPS mailing service?

Regards.

I'm having problems with my VPS (WHM+Cpanel) and a mailing list I manage using PHPlist + Xoops/ImpressCMS -> PHPList brigde module. Everything was working fine, but I think the last mailing I sent failed, despite what PHPList report said.

To track the problem, I'd like some way to track all mails received and sent in, say, one hour. Something like:

"Show me a list of all mails sent and received in the last hour, and tell me what happened to them."

How could I do this?

Does PHPList keep track of those emails?
Maybe the SMTP server kept track of those emails

Actually, PHPList documentation says they are sent using sendmail by default. I digged into the docs and found a way to change sending mehtod to SMTP. It's a blind shot, let's see what happens.

BTW, I don't know how to look SMTP server logs, registry or whatever it has. I'm lost on this.