I went through a lot of hassle getting ours to work too. Because I work for such a large company (Northrop Grumman) it was surprisingly difficult, given all the permissions and firewalls.
Here are some of the things I tried when figuring out our email. Hopefully they will point you in the right direction.
First, did you get the name and port number of your email server from your IT people? They are probably the only ones that would know it. Can they verify the information provided works with their tools?
Second, can you PING the email server? Before worrying if EPDM can see it, can your computer see it?
It may not be the same server your IT people would like you to use, but if you are using Outlook you can see the name of the Microsoft exchange server in email account settings. Does that server address work? I'm not sure if this a good approach.
It ended up being our virus scanner softward.