Can I make "sendmail" use another name != 'hostname` ?

[John McKiernan]

We have several systems behind firewalls or using private (RFC-1918; 192.168.x.y) addresses on some interfaces. The system name as seen via "hostname" is often using these private addresses and DNS staff don't want those names/addresses in DNS. But if
the same system sends mail, it goes out as if it was from a system not in DNS , and reverse lookup from relays fails. When that fails, the message is refused, and mail is blocked.

How can I get "sendmail" to send messages using another source address/name which is in DNS but is *NOT* the "hostname" ? I created a "Dj" record in "sendmail.cf" and set a FQDN for the outgoing interface in /etc/hosts . But the messages in local logs and the returned mail still show "sendmail" used the
"hostname" data.

[Stuart Browne · Accepted solution]

MASQUERADE_DOMAIN(`your.external.domain')

in your MC file, re-make your CF files and try again.

[Lawrence Staberg]

The correct sendmail.cf code is DM{FQDN} not Dj. And is not normally setup in the default cf files on Redhat.. Use the mc file and ADD the code in the previous post..

[Steven E. Protter]

You can do a manual edit of sendmail.cf or you can do it with sendmail macros.

Attaching the script to let you follow Stuart's recommendation.

SEP

[John McKiernan]

Never found a solution, so we added the required source names to DNS as a (bad) workaround.