Sendmail not sending and DNS

[bhm8hwcm]

I am having a problem with Sendmail - message are not being sent from either the command line or Webmail.

Relaying appears to be happening through localhost and my logs show that the message is accepted for delivery.

The messages do not get delivered though and this is part of the error message :
stat=Deferred: 450 <barry@localhost.localdomain>: Sender address rejected: Domain not found

Is the problem because of the localhost.localdomain? Should this be changed to something else?

It seems as though all mail is being sent from localhost.localdomain. I will be hosting 3 different sites that need to send mail so I am not sure what I need to change. I have not set up DNS and I am not sure if I need to. When I registered my Domain names, my provider pointed the domain names to my static IP address for the sites (virtual hosted). Do I not therefore need to set up DNS on my server.

Is my Sendmail problem DNS related at all.

Thanks

[aprmgr]

You need to define DNS for the particular domain. Have you mentioned
the IP add / domain name in /etc/local-host-names file.
or have you given relay to your domain in sendmail.cf
check it... I think there is a problem