553 Bounces and SMTPD

[ruffbunka]

Hi there,

New to Scalix, managing a client's install. Can anyone please advise on this situation.

We have a number of linux machines on the internal network which send mail to our scalix user's mailboxes. When the mail is sent, it is from root@machine_name.domain.com and Scalix returns a 553 domain does not exist bounce. I believe that this is because the machine names are not available for lookup as they are not stored in DNS.

I believe that we need to alter our smtpd.cfg, however I would appreciate a confirmation and any assistance / recommendations.

Thanks in advance.

[ScalixSupport]

You are getting that 553 error because there is neither an A nor an MX for that machine.
An A record is enough, sendmail just wants to be able to resolve the host.

If you add hostnames in your access that sendmail can't resolve, then it doesn't know
which host that is from which it should accept mail. That's why your access doesn't
work. If you use the @domain syntax in the access that would fly, but not hosts it can't
resolve. The access isn't designed to fix dns problems, but rather to provide host based
access control. It's not access control if I can claim to be securehost.yourcompany.com
but am really evil.attacker.net ....

The quick and dirty fix is to disable that check by adding

dnl FEATURE(`accept_unresolvable_domains')dnl

to either sendmail.mc or submit.mc (depends on distro - don't have a CentOS on hand to test) then restarting sendmail (the sendmail init script should rebuild your conf automatically) then running omsendin to add the scalix specific stuff to sendmail. If that
doesn't work, try deleting sendmail.cf and submit.cf by hand and restarting the daemon again, then omsendin again.

The *clean* fix would be to simply make host.company.com resolve to an ip address. All sendmail wants is an A-record for that host in DNS. If you can dig -t any the host and get an A or an MX back, you're golden.

Hope this helps.

Regards,
Subir