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sendmail & dns with multiple distinct mail services in a single domain

harry d brown jr
Honored Contributor

sendmail & dns with multiple distinct mail services in a single domain


We have two mail services - one for user mail (smtp.FULLDOMAINNAME - (which is comprised of many actual mail servers)) and another for server to server mail delivery (which uses openmail).

The latter (openmail - that does server to server mail delivery) is used to deliver data from one machine (HPux server) to another (HPux Server). Eventually we will replace the openmail, but this is not an option available to us at this time (unfortunately). Openmail works, and has worked for us for the past 10 years with very little issues. We are probably still the largest openmail licensee in the world. We also used to have it on our desktops (UGLY). Now with that stated, let me get the the issue.

Issue: sendmail attempts to retreive the MX record for our OPENMAILserver, but the only MX record is for our smtp.FULLDOMAINNAME server. So sendmail first queries DNS for "OPENMAILserver", it gets a response back saying that there is no MX for "OPENMAILserver.FULLDOMAINNAME". Sendmail then asks DNS for "OPENMAILserver.FULLDOMAINNAME.FULLDOMAINNAME" - which of course does not exist (sample: oms.aol.com.aol.com).

Can I add a specific MX record to DNS that says the following:

OPENMAILserver IN MX 10 OPENMAILserver.FULLDOMAINNAME.
OPENMAILserver.FULLDOMAINNAME IN MX 10 OPENMAILserver.FULLDOMAINNAME.

Or is there something in sendmail.cf that I can configure to tell it not to lookup MX records because I already know that I want to forward mail to OPENMAILserver??

live free or die
harry
Live Free or Die
7 REPLIES
Steven E. Protter
Exalted Contributor

Re: sendmail & dns with multiple distinct mail services in a single domain

The first thing I'd try is the DNS record your are proposing.

Trying to get sendmail.cf to ignore DNS or not do a lookup doesn't sound like a profitable course of action.

I'm running 13 domains on on web server, mail included and thats how I'd proceed.

Your proposal should distinguish properly between smtp.FULLDOMAINNAME and OPENMAILserver.FULLDOMAINNAME

You might be able to bypass the domain entries with entries in the /etc/mail/aliases file

@openmailserver: username

username has a .forward file pointing to the IP address of the openmailserver.

SEP
Steven E Protter
Owner of ISN Corporation
http://isnamerica.com
http://hpuxconsulting.com
Sponsor: http://hpux.ws
Twitter: http://twitter.com/hpuxlinux
Founder http://newdatacloud.com
Jeff Schussele
Honored Contributor

Re: sendmail & dns with multiple distinct mail services in a single domain

Hi Harry,

Assuming that you have the OpenMail delivery agents set up properly on these hosts - which you must as sendmail is delivering it somewhere & not rejecting it - then the other question should be...Are you using the DQ option in sendmail.cf to denote the OpenMail relay?
I'm not sure if this will require DNS resolution or not, but I'd think that it would be safe if it was in there with an MX record.

Also you should look at the rulesets in the sendmail.cf file that deal with OpenMail.
These are around line 1366 in the 8.9.3 sendmail.cf file or search on "OpenMail".
You can manipulate the delivery in there as well - although sendmail rulesets make my eyes glaze over ;~))

HTH,
Jeff
PERSEVERANCE -- Remember, whatever does not kill you only makes you stronger!
Helen French
Honored Contributor

Re: sendmail & dns with multiple distinct mail services in a single domain

This document will be useful (TKb # UMAILKBRC00009913):

http://www2.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000062922179
Life is a promise, fulfill it!
harry d brown jr
Honored Contributor

Re: sendmail & dns with multiple distinct mail services in a single domain

Thanks guys, I'll look into these tomorrow and get back to ya!

live free or die
harry
Live Free or Die
Kasper Haitsma
Trusted Contributor

Re: sendmail & dns with multiple distinct mail services in a single domain

Hello,

Which flavour of client one prevers, is very personal. HP supplies various clients (OMGui, web client) as well as interfaces for clients (IMAP, POP, MAPI). In the past there were customized versions of other vendor's mail clients (MicroSoft's MSMAil and Lotus's cc:Mail).

There are several ways to solve your problem.

The easiest, is Steven E. Protter's. You need to make sure the different OpenMail servers are (MX) resolvable, either through /etc/hosts, or DNS configuration. I wander how you have gotten by, over the past 10 years, without name resolving?

Beware, the DQ parameter is only to be used, when there is not an OpenMail instance on the local hosts! Otherwise looping messages will be the result. I can explain this in more detail, when interested, but for now I advise you not to use DQ, if you have OpenMail on the local machine.

There are more complex ways of resolving this, using mailertable or smtp.hosts features of sendmail, but this only complicates matters. Or you could even have the OpenMail to OpenMail service (omstat(1)'s Sendmail Interface, omshowrt(1)'s SMINTFC {or omaddrt, omdelrt, ommodrt}) use it's own customized sendmail.cf. See /var/opt/openmail/sys/xport.mappers/XPORT. You could add
-C
to the sendmail line.

HTH

Kasper Haitsma
HP support engineer for OpenMail & sendmail
It depends
harry d brown jr
Honored Contributor

Re: sendmail & dns with multiple distinct mail services in a single domain

I think we are going to try to stop sendmail from using MX records. As soon as we get it working, I'll post the solution.

live free or die
harry
Live Free or Die
Kasper Haitsma
Trusted Contributor

Re: sendmail & dns with multiple distinct mail services in a single domain

Hi Harry,

If you want to disable MX, you'l need to add 0 (zero) to the mailer Flag(s). Since the regular esmtp mailer is used for OM system to OM system communication, you need to catch a mail attempt to openmail@remote_system in the Rules, and instead of the relay mailer, or esmtp mailer, you invoke your own mailer (copy of esmtp mailer), where you add the 0 (zero) to the Flag list.

Mmyom2om,.....F=0......

Two general cotha's, not particularly for you, but they do apply here as well:
1) sendmail.cf lines are delimited!!
2) document these changes, so you can apply them in a next version of sendmail.cf (in principle, you can use an 'older' version of sendmail.cf, but it might not make use of the newer features, when one has installed an upgrade)

HTH

Kasper
It depends