Why sendmail is accepting mails for hostname not present in local-host-names file?

Question

I have following line in my cf file

Fw/etc/mail/local-host-names

and following lines in local-host-names file

mydomain.com
hostname.mydomain.com

but when I send mail to [email protected], sendmail is accepting mails for it. otherhost.mydomain.com resolves to one of the private IP address. What could be the reason?

Solution

In your prompt type:

$ sendmail -bt
> $=w

$=w is a class that contains all the names sendmail considers local. These include those listed in /etc/mail/local-host-names and those in /etc/hosts that sendmail considers local after examining the machine's network interfaces.

Comments

[David Schwartz]

What do you mean by "is accepting"? Do you mean it's delivering the mails locally?

[Sachin Divekar]

No if I try to send mail by accessing SMTP using telnet, for rcpt to it says recipient ok. It should say user unknown right?

[Sachin Divekar]

thanks a lot. sendmail is considering otherhost.mydomain.com as local after observing network interface. It is a PTR record for IP addresses on one of the ethernet interfaces.

[AnFi]

There is an option to turn off "auto detection/adding" local email domains (DontProbeInterfaces).

[Sachin Divekar]

@AndrzejA.Filip thanks a lot for your suggestion. Yes, I verified DontProbeInterfaces is False in my case.

[AnFi]

Is otherhost.mydomain.com a CNAME DNS record? YES => sendmail rewrites CNAMEs (DNS aliases) to "true names".