Mail using postfix receive but cannot send

[garfabian]

Hello
First time user of ISPConfig and loving it, I have two problems

(1) when users are created their emails are set in the format of user@www.domain.com how can I set this up so that when users are created their emails are user@domain.com?
(2)if I sent out an email from user@www.domain.com to let say user@msn.com it never reaches but if I sent an email from user@msn.com to user@www.domain.com I then reply to it then user@msn.com can see it.


Can anyone please let me know what is it that I'm doing wrong.
I have a fedora 4 perfect setup running postfix and maildir enable.
Thank you.