Mail Server Assistance Needed

[Manny]

I just finished configuring 'n setting up Postfix as my mail server.
I'm sure I've missed a few things, but I'm not sure exactly WHAT?

I'm able to send mail just fine. I've done a few tests sending email
to my webmail accounts, like yahoo or gmail. If I reply from either of
these accounts I never see the email on my server. And I don't get a
bounce message back. So where is that email message at? And how do I
retrieve it.

Also, are there any thing I need to do with imap? I'm just a lil lost
at this point.