Cannot send emails with sendmail

When I send email with sendmail I have it back with this error:  
----- The following addresses had permanent fatal errors -----
    (reason: 501 <>... Sender domain must exist)

I know that this machine is called cob327 but I don't know where to put my virtual domain to work with sendmail.

Please help.

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markt9Connect With a Mentor Commented:
add a A record to your dns for your sendmail box's ip

cob327    IN     A

your dns should already have a record for

That error is from the remote SMTP server you tried to deliver the message to. And the remote server is telling you that it won't accept the message from you because your system (apparently can't be resolved via DNS. And in fact if I attempt "nslookup" I get "server can't find NXDOMAIN". For you to be able to send email from that system you need to have your machine listed as bein in by whoever manages the DNS of
CurieuxAuthor Commented:
Thanks for the help.

In fact I know that this domain name is not valild.
I have another domain working that I want to use instead of And I want all the mail be sent from this new domain. How to change the sendmail configuration to send from the new domain.

jlevieConnect With a Mentor Commented:
If you make tell the SMTP server that it is in that new domain and that the DNS records for the domain contain the A & PTR record for your SMTP server (as markt9 said), then sendmail will automatically send the email from that domain.

There are other solutions possible if the system running sendmail can't be made a member of this registered domain.
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