Why does sendmail 8.14.4 appear to be ignoring MX weight when connecting to remote mail servers?

mike.b...@yahoo.com

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Apr 24, 2013, 10:53:05 AM4/24/13

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As a test, I intentionally blocked firewall access for a lab server and tried sending a message to a test account on yahoo.

Check it out:

[root@foobox ~]# mailq
/var/spool/mqueue (2 requests)
-----Q-ID----- --Size-- -----Q-Time----- ------------Sender/Recipient-----------
r3O3cqEm011098 51218 Tue Apr 23 20:38 MAILER-DAEMON
(Deferred: Connection refused by alt4.gmail-smtp-in.l.google.)
<foote...@gmail.com>
r3NMd1Em011926 48807 Tue Apr 23 15:39 <foote...@gmail.com>
(Deferred: Connection refused by mta5.am0.yahoodns.net.)
<foote...@yahoo.com>
Total requests: 2

[root@foobox ~]# sendmail -v -d17.9 -q...@yahoo.com

Running /var/spool/mqueue/r3NMd1Em011926 (sequence 1 of 1)
hostsignature(yahoo.com.)
mxrand(mta6.am0.yahoodns.net) = 20
mxrand(mta7.am0.yahoodns.net) = 89
mxrand(mta5.am0.yahoodns.net) = 140
hostsignature(): getmxrr() returned 3, mxhosts[0]=mta6.am0.yahoodns.net.
hostsignature(yahoo.com.) = mta6.am0.yahoodns.net.,mta7.am0.yahoodns.net.,mta5.am0.yahoodns.net.
hostsignature(yahoo.com.)
hostsignature(): stab(yahoo.com.) found mta6.am0.yahoodns.net.,mta7.am0.yahoodns.net.,mta5.am0.yahoodns.net.
<foote...@yahoo.com>... Connecting to mta7.am0.yahoodns.net. via esmtp...
<foote...@yahoo.com>... Connecting to mta5.am0.yahoodns.net. via esmtp...
<foote...@yahoo.com>... Connecting to mta6.am0.yahoodns.net. via esmtp...
<foote...@yahoo.com>... Deferred: Connection refused by mta6.am0.yahoodns.net.

It correctly identifies the MX preference but what I don't understand is why the verbose output shows it connecting to mta7 and mta5 FIRST (both of which have a higher MX value). What does that mean?

Claus Aßmann

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Apr 24, 2013, 12:32:44 PM4/24/13

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wrote:

> [root@foobox ~]# sendmail -v -d17.9 -q...@yahoo.com

> It correctly identifies the MX preference but what I don't understand is why the verbose output shows it
> connecting to mta7 and mta5 FIRST (both of which have a higher MX value). What does that mean?

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

dig shows all of them are the same:

yahoo.com. 1800 IN MX 1 mta7.am0.yahoodns.net.
yahoo.com. 1800 IN MX 1 mta5.am0.yahoodns.net.
yahoo.com. 1800 IN MX 1 mta6.am0.yahoodns.net.

So what do you see on your system?

Mike Berggren

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Apr 24, 2013, 9:10:45 PM4/24/13

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>
> So what do you see on your system?

You're right. I see them as 1. I'm further confused now... what is 20, 89, and 140 referring to in the following output -d17 debug output:

Chris Adams

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Apr 24, 2013, 9:54:42 PM4/24/13

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Once upon a time, Mike Berggren <mike.b...@yahoo.com> said:
>You're right. I see them as 1. I'm further confused now... what is 20,
>89, and 140 referring to in the following output -d17 debug output:
>
>mxrand(mta6.am0.yahoodns.net) = 20
>mxrand(mta7.am0.yahoodns.net) = 89
>mxrand(mta5.am0.yahoodns.net) = 140

I expect "mxrand" is MX randomization (sendmail needs to do something
random when given multiple MXes at the same priority).
--
Chris Adams <cma...@hiwaay.net>
Systems and Network Administrator - HiWAAY Internet Services
I don't speak for anybody but myself - that's enough trouble.