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Mail relay from: address resolution

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Mail relay from: address resolution

I have an issue I am trying to resolve in configuring a mail relay.

If a client sends an email with the FROM: address as "user@abc.com" my relay blocks it since "abc.com" does not resolve ("server.abc.com" does, however).

If the client sends an email with the FROM: address as "user@server.abc.com", it will pass through my relay, but will be blocked by outside mail systems, since "server.abc.com" does not resolve (it's an internal only address).

I have tried putting in "abc.com" in the host tables so that it resolves to something, but the mail is still not going through. I may revisit this, now that I have more detailed logging turned on, but ideally, I would like to have sendmail not try to resolve the FROM: address. Older versions of sendmail didn't do this, it appears to be a new default in sendmail. I have tried setting:
O PrivacyOptions=public
in the sendmail.cf file, but this has no effect. I suppose I could create a new .cf file from the .m4, but I am hoping there is an option setting in sendmail.cf that I am missing.
Any assistance would be appreciated. Thanks!
4 REPLIES
Geoff Wild
Honored Contributor

Re: Mail relay from: address resolution

Set the DM macro on both servers /etc/mail/sendmail.cf:

# who I masquerade as (null for no masquerading) (see also $=M)
DMabc.com

Then restart sendmail...

Rgds...Geoff
Proverbs 3:5,6 Trust in the Lord with all your heart and lean not on your own understanding; in all your ways acknowledge him, and he will make all your paths straight.
Sanjay_6
Honored Contributor
Solution

Re: Mail relay from: address resolution

Hi Steven,

you can allow your mail server to accept mails from abc.com for relay.

this link from itrc might help,

http://www1.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000062922173

The itrc doc id is UMAILKBRC00009719

Hope this helps.

Regds

Re: Mail relay from: address resolution

> Set the DM macro on both servers
> /etc/mail/sendmail.cf:
>
> # who I masquerade as (null for no
> masquerading) (see also $=M)
> DMabc.com
>
> Then restart sendmail...
>
> Rgds...Geoff

Geoff -
This didn't work, since, even though the mail relay masquerades as abc.com, the FROM: address still does not resolve.

Thanks for the idea, though!

Re: Mail relay from: address resolution

>Hi Steven,
>
>you can allow your mail server to accept mails
>from abc.com for relay.
>
>this link from itrc might help,
>
>http://www1.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000062922173
>
>The itrc doc id is UMAILKBRC00009719
>
>Hope this helps.
>
>Regds

That's exactly what I'm looking for! All I need to do is run the gen_cf script and have it generate a sendmail.cf with Accept_unresolvable_domains turned on.

Thanks!

Steven