I am experiencing a very weird problem with a mail server that I maintain. When I try to send an email from a.com to b.net (I.E. :1@a.com sent email to 2@b.net) the a.com server sends me back a responce saying that 2@a.com does not exist and does not send the email. a.com server and b.net server exist on the same network. When I try to setup and alises for sendmail to use I get the same thing. (I.E.

root: postmaster
1: 2@b.net
)

Any ideas why a.com thinks 2@b.net is an address that exists as 2@a.com?

Same thing happens with telnet

telnet a.com 25
EHLO b.net
250-a.com Hello localhost [127.0.0.1], pleased to meet you
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-EXPN
250-VERB
250-8BITMIME
250-SIZE
250-DSN
250-ETRN
250-DELIVERBY
250 HELP
MAIL FROM: 1@a.com
250 2.1.0 1@a.com.. Sender ok
RCPT TO: 2@b.net
550 5.1.1 2@b.net.. User unknown
quit

2@b.net can recieve email from everywhere else but this one machine.

Please help.

Please check where does the MX record for 2.net point to in your DNS server.

Cause if MX record for 2.net points to 1.com as the mail server then the mail would be sent back to 1.com for delivery.

Also see if 2.net is an alias for a.com in the dns.

This could be one of the possible issues.



.... Nitin Batta ....
http://nitinb.blogspot.com

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I've check all the DNS records for both domains.

a.com MX 20 mail.a.com

b.net MX 20 mail.b.net

Don't use CNAMES at all as they are bad juju.

IP for a.com match

a.com IN A 1.1.1.1
mail.a.com IN A 1.1.1.1

b.net IN A 2.2.2.2
mail.b.net IN A 2.2.2.2

Just login to a.com as user 1 and open aanother telnet / ssh session to a.com as root and do a tail on mail log files.

now send a mail from 1@a.com to 2@b.net using your fav client and check what error does sendmail actually throw in the logs.

This can provide some light on the issue.

to=2@b.net mailer=relay stat=User unknown
from=root@a.com relay=localhost

Hi
Just try the nslookup to check whether the dns entries you have put resolve correctly.

Can you post your sendmail.mc and aliases file for more debugging.

Did you ran newaliases when you set up the aliases file?