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Re: master mail problems -- help needed

This one time, at band camp, Florian Weimer said:
> >From time to time, master seems to bounce mail routed to mail.enyo.de
> with the following error message:
>   fw@deneb.enyo.de
>     retry time not reached for any host after a long failure period
> Is anybody experiencing a similar problem?
> I tried to debug it myself, using the information I could access on
> master, but I couldn't gather enough evidence to present to the
> postmasters so far.  IIRC, when there are no prolonged connectivity
> problems, the error message is characteristic of a broken Exim retry
> configuration (no retry section at all, or something like that), but
> master's configuration seems to be fine in this regard.

You want to try 
/usr/sbin/exim4 -brt deneb.enyo.de 

You'll get an answer back that looks something like
F,2h,15m; G,16h,1h,1.5; F,4d,6h;

This means retry every 15min for the first 2 hours, then go into a 'growth
algorithm' period where you retry starting at 1hour, then multiply by 1.5
until 16 hours have elapsed (so first every hour, then 1.5 hours, then
2.25 hours, etc) then finally every 6 hours until 4 days have elapsed,
then bounce the mail.

Once you know the retry rules, try 
/usr/sbin/exinext fw@deneb.enyo.de

That will tell you what's recorded in the retry database currently.
It's fairly self explanatory, and you'll get something that looks like:

Transport: gateway1.att.net [] error 0: SMTP error from remote mailer after initial connection: host gateway1.att.net []: 450 busy - please try later
  first failed: 26-Nov-2005 15:35:16
  last tried:   26-Nov-2005 15:35:16
  next try at:  26-Nov-2005 15:50:16
Transport: gateway2.att.net [] error 0: SMTP error from remote mailer after initial connection: host gateway2.att.net []: 450 busy - please try later
  first failed: 25-Nov-2005 04:44:32
  last tried:   26-Nov-2005 15:35:16
  next try at:  26-Nov-2005 21:35:16

I am guessing that you'll find that your host should have been tried
and wasn't.

> The host mail.enyo.de had some intermittent connectivity problems
> during the past few weeks (downtimes of about one hour every couple of
> days, nothing which should cause Exim to run past its configured retry
> limit).  But this has been fixed, and the sporadic bounces continued.
> The other problem is a certain sluggishness when one of those botnets
> attempts to send spam to hundreds of message IDs, but these attacks
> last a couple of minutes only, and master should be able to cope with
> that.

I am guessing here, since I don't really have any way to check, but I
assume that the problem is related to master's large queue.  If exim
encounters a host down state, it records it in the retry database.
The host state will be updated, but only when the queue finally reaches
it after the retry timer expires.  If the queue takes forever to process,
it's possible for host states to last longer than they should.

Good luck, and hope that helps,
|   ,''`.                                            Stephen Gran |
|  : :' :                                        sgran@debian.org |
|  `. `'                        Debian user, admin, and developer |
|    `-                                     http://www.debian.org |

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