mail server

I need to find out what mail server I have. Google says that I should just figure it out based on my ISP, but I'm at work and my job has its own network. Is there someway to just find out for certain what mail server I have?

So there's lots of unusual traffic in our exchange server, spam being received and sent all the time, from and to different IPs, it's just a matter of time before we get blocked by pretty much everyone...

I'm just an above average user doing tech support... what I've done so far is checking that exchange's configuration doesn't allow open relay... and used wireshark to watch traffic a little bit... I can see a lot of traffic but have no clue about what else to do...
I've followed every tutorial I've found to correct exchange's configuration.. clueless already

any ideas guys?

sory i'm stupid