senders address rejected: domain not found

[tanya]

I can receive e-mails, but can not send e-mails. whenever i try to send an
e-mail, i recieve an error message saying the following:
Trudie ([email protected]) on 2007/06/20 11:37 AM
551 5.1.8 <[email protected]>: Sender address rejected:
Domain not found

Could someone please tell me what to do to fix this problem?

 

[David Biddulph]

It means that the domain concretworkssa.co.za from which you are trying to
send has not been registered.
Did you intend to use concreteworkssa.co.za, which has been registered?

 

[Diane Poremsky]

it could mean that nwk.co.za is using DNS lookup and they only accept mail
from valid domains and your domain is not in the list they are querying so
it comes back as invalid.