sendmail not getting through proxy server

[Steve Post]

I have sendmail on hpux11 box. The reverse dns lookup entry for this box is not known to the internet, nor will it be. It has an internal entry. Let's call it mybox.company.com. The mail goes through a windows NT proxy server. Let's call this mail.company.com.

When mail is sent so SOME websites, they kick it back because it can't resolve mybox.company.com.

In linux, the solution would be to add FEATURE('nullclient','mail.company.com') in file sendmail.mc. But in HPUX there is no sendmail.mc file.

In mybox.company.com:/etc/mail/sendmail.cf...
#Dj$ not used.
DSmail.company.com

I would like the mail to be from mail.company.com when going out to the world, but stay mybox.company.com when inside.

Anyway to do this?

[Robin Wakefield · Accepted solution]

Hi Steve,

There is a nullclient feature. The O'Reilly book documents how to set this up, but basically you create a 3-line null.mc file, e.g.

include('../m4/cf.m4')
OSTYPE('sunos4.1')
FEATURE('nullclient','mail.company.com')

then m4 null.mc > client.cf

Rgds, Robin.

[Sridhar Bhaskarla]

Did you try the Masquerading option?.

Enable DM macro in your sendmail.cf
file?
For your localdomain you use CM macro.
So, it will not masquerade for your local domain

DMyourdomain.com
CMyourdomain.com

This should fix your problem

-Sri

[Steve Post]

I did not try the nullclient feature because I did not know where to put it. I did try the the CM macro, and that worked. ...as long as I'm not sending the mail as root. (I should NOT send as root anyway).

But here's an question I that came out of this. What if I send to a bogus email account? It would try to respond back to me@mail.company.com, a bogus account. So, I would never know I never made it right?

I really have a good email address in the From: field. But it looks like it uses the "Return Path instead. Anyway to insist it reply to the legitimate from-field instead of the bogus Return-Path?

[Sridhar Bhaskarla]

Steve,

I am not sure if this can be applied to your setup. The way in which our site is setup that we keep aliases on the name server.

For example, on all our systems, we do site hiding by enabling DM and CM macros. So whenever a mail is sent from this system, it goes as

me@mydomain.com

Now, when people reply to this mail, it first gets into my name server (because it is addressed to mydomain.com) where "me" is aliased to "me@mysystem" and reaches me. Then it will be forwarded to "me" on "mysystem".
We don't have to worry about internal mail as my CM macro will take care of it.

This way we can have good control over the mail.

I didn't use nullclient feature either.

-Sri

[Ralf Hildebrandt]

There's a sendmail.mc:

% find / -name '*.mc'

even on HP-UX

[Steve Post]

There is no sendmail.mc file on this system. But that's ok. It works good enough for now. Perhaps the version of sendmail I have is old.

The outbound email works thanks to
"DM legit.dns.name". Where legit.dns.name is where I put my real dns name.

Thanks for the help.
Steve