[Mailman-Users] Erratic mail delivery times

[Mark Sapiro]

On 07/14/2014 06:55 PM, Barry S. Finkel wrote:

> On 7/14/2014 8:43 PM, Peter Shute wrote:
>> Would grey listing show up in the headers? We haven't installed grey
>> listing here, but who know what our anti spam does.


Greylisting may or may not show in headers depending on the software
doing it. For example, Postgrey adds a header like

X-Greylist: delayed 427 seconds by postgrey-1.34 at sbh16.songbird.com;
 Sat, 12 Jul 2014 18:14:34 PDT


>> If it's using it
>> then it certainly isn't using it consistently. I can't see anything in
>> the Exchange Message Tracking logs that shows anything unusual as they
>> come in. They simply arrive late.


See below.


>> I dumped from Outlook the last few weeeks of send and received times
>> for stuff I've received from this list. Some of the delays will be
>> moderation time, but I can see that the number of messages delayed
>> longer than a few minutes increased greatly on 11/7/14, but that there
>> is still the occasional one that comes though within a minute.


This could be due to greylisting. Intelligent greylisting keeps track of
sending servers, and after a server has successfully retried a small
number of messages, there is no point in further greylisting that server
because the server is known to retry.


>> These are the top two headers from a delayed message. Does this tell
>> me anything other than it was received by the server upstream of mine
>> 21 minutes before it was received by mine? If so then the delay could
>> be before that upstream server sent it on, or while it waited for my
>> server to accept it. If it tried several times, would that be shown in
>> the headers?


You are correct, the delay was in transmission from the upstream server
to your exchange server. The headers tell you nothing more than that.

However, in this case, if greylisting is involved, it is your exchange
server doing it and there should be evidence in the exchange server's
logs of the initial connect and temporary reject at about the time the
upstream server received the message and initially tried to relay it.

Of course, there can be other reasons such as network issues why the
sending server's initial sending attempt failed, and these may not be
logged in your server. You'd have to see the logs of the sending server
to know what happened and why in these cases.

...
> Twenty minutes seems
> a long time for greylisting.


There are two times involved in greylisting. The first is the recipient
(greylisting) servers "early retry" time, i.e. the time before which the
server says this retry is too soon. That is typically short, on the
order of 5 minutes.

The second is the delay before the sending server retries. This depends
on the retry strategy of the sending server and can easily exceed 20
minutes.

-- 
Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan