backup mx: weird errors when flushing queues

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chris
Posts: 3
Joined: Mon Oct 17, 2005 10:54 am

backup mx: weird errors when flushing queues

Post by chris »

Hi there,

first of all thanks for your great service! The below issue refers to the domain 'deckfour.org' which is registered under user id 'kingfries' on your system.

I have experienced a power failure this afternoon, due to which my mail server went down. After that some 10 messages were buffered on your backup mail servers, which I manually tried to dequeue using the web form provided by you.
During that, I monitored my sendmail log, which showed the following messages:

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Oct 17 17:50:10 nina sm-mta[8658]: j9HFoAcI008658: mail2.rollernet.us [66.224.163.2] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
Oct 17 17:58:39 nina sm-mta[32444]: j9HFwdpa032444: mail.rollernet.us [208.11.75.2] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
Oct 17 17:58:53 nina sm-mta[32041]: j9HFwr1Z032041: mail2.rollernet.us [66.224.163.2] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
Oct 17 17:58:53 nina sm-mta[2202]: j9HFwr71002202: mail2.rollernet.us [66.224.163.2] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
Oct 17 17:58:58 nina sm-mta[20990]: j9HFwweY020990: mail.rollernet.us [208.11.75.2] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
Oct 17 18:10:45 nina sm-mta[9472]: j9HGAjEg009472: mail.rollernet.us [208.11.75.2] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
Oct 17 18:10:49 nina sm-mta[16473]: j9HGAnr0016473: mail2.rollernet.us [66.224.163.2] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
Oct 17 18:10:50 nina sm-mta[18980]: j9HGAoOX018980: mail2.rollernet.us [66.224.163.2] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
Corresponding to that, the mail log displayed in my account on your site shows various errors, where the 'Response' field reads like:

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deferred (connect to deckfour.org [85.145.80.56]: read timeout)
I can receive mail without problems from third-party sites (i.e., direct delivery), so sendmail as-is appears to work fine. However, this is the first time I actually employ a backup mx server in my mail setup. The DNS entries should be just fine as well, from what I understand in various documentations.

My question to you is:

- What does the message in your logs mean ('deferred'), has my mail gone to /dev/null or is it still caught in some buffer? (I have positively not received mail from your servers).
- Are there specific options in the sendmail configuration that I may have missed?

Sorry if this is a newbie issue, but I am not too familiar with sendmail setup and mail backup so far.
Any help is greatly appreciated.

Cheers, Chris
RollerNetSupport
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Post by RollerNetSupport »

Thanks for the detailed information!

This appears to be something that I can fine tune on our end. I've increased the initial server response timeout to 300 seconds; please let us know if you are still seeing the same errors.
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Roller Network LLC
RollerNetSupport
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Post by RollerNetSupport »

You should also probably turn off the "Slow Delivery" option unless you really need it; according to a simple test (telnetting to port 25 and watching the clock), your mail server responds within 5 seconds.
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chris
Posts: 3
Joined: Mon Oct 17, 2005 10:54 am

Post by chris »

Thanks for the swift reply!

As for the slow delivery option, I had only enabled it after the error occurred, trying to prevent timeouts. In the meantime I have done more extensive web searches and stumbled upon this usenet thread:

http://groups.google.com/group/comp.mai ... rt=0&num=3

To sum things up as I understood it, the issue in the above case was that a server identified itself as 'localhost.localhost', the backup mx server had the same identification. At least in the posts it is hinted that this might have been the issue there.

Now for my setup:
- My sendmail identifies itself as 'nina.deckfour.org'
- In my DNS zone information I have 'deckfour.org' as an A record, 'nina.deckfour.org' as a CNAME.

However, I suppose that the mismatch between deckfour.org and nina.deckfour.org could hardly make your server abort the connection, or would it? At least I would rule out an abort on my side, as the machine happily accepts posts for *@deckfour.org

I have killed sendmail after posting the initial message here and sent some test emails to be backed up by your servers. 20 minutes later I started sendmail again. I have seen the test mails in your server's icoming logs, but they have not been transmitted yet. I assume that, given the time having passed, there should have been a retransmission attempt in the meanwhile.

Judging from your experience, is this still 'normal' behavior?
In any case, I'll wait some more and keep an eye on that thing.

Thanks again, and greetings from the Netherlands,
Chris
chris
Posts: 3
Joined: Mon Oct 17, 2005 10:54 am

Post by chris »

Hi,

Yesterday night the backed up test mails dropped in one after another, as I would have expected. I have no clear idea what the problem was, but I hope things will just work fine from now on :)

I still have no clear idea for what happened to the originally backed up mail which was buffered when my machine went offline, probably I received it as well (they might just have been killed by spamassassin).

Thanks again for your excellent service and support! Keep up the good work and have a nice day,
Chris
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Post by RollerNetSupport »

It should work transparently. When it was in slow mode, the mail was waiting for a different delivery process. It can take a little time for it to back out and re-queue for a standard delivery slot.
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Roller Network LLC
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