Mail Server error 553
 

i have installed ubuntu server on a machine and done the DNS changes etc and setup postfix etc. Im not sure if i have missed someting or whats going on but if i try to send an email to the server i get the following error back

The following message to <mail@domain.co.uk> was undeliverable.
The reason for the problem:
5.1.0 - Unknown address error 553-"sorry, that domain isn't in my list of allowed rcpthosts; no valid cert for gatewaying (#5.7.1)"

what am i doing wrong

hi friend
i am very new to RHEl
on the time of downloading vlc player the following earror is occered
"Apache/2.0.52 (CentOS) Server at rpmforge.sw.be Port 80"
please help me