email working howto

problem:
First thanks for this project. I have installed EHCP in Ubuntu Server 8.04. Everything is working fine. But I have problem with E-mail sending. I have rechecked/reconfigured the postfix configuration file. But still I am not able to send e-mail from my server.
Please help me or send me some documentation to solve this problem.

Thanks,

suggestion/answer:
Please write here, how you test to send email, using webmail or a mail client ?
do you use email username like user@domain.com, it should be like this...
from which network do you try to send email, if you are trying to send email from the same network that your server exists, then you need some additional things..

please use forums for support requests, so that everyone gets useful info..

see you.