On Wed, May 06, 2020 at 09:07:45AM -0400, Wietse Venema wrote:
> You need to collect logs over at least 5 minutes.
I was sitting this one out, but perhaps should make a few comments:
1. Postfix does not have bugs of the sort conjectured by the OP.
The problem is entirely a result of configuration and workload.
2. I don't recall seeing the OP's configuration (verbatim, without
refolding of lines, "postconf -nf" and "postconf -Mf" output)
posted to the list.
3. Frequent routine "postfix reload" is a bad idea. On queue
manager restart moves all active messages back into the
deferred queue for reprocessing, this is disruptive.
Don't do that.
4. The queue manager suspends requesting delivery of new mail when
all the transport delivery agents are still busy attempting
to deliver previously scheduled deliveries.
5. The queue manager also suspends delivery to a transport when
the delivery reports fatal errors.
6. The queue manager suspends delivery to a particular nexthop
destination when enough back to back deliveries to that
destination fail (not just invalid recipients but failure
to complete the mail transaction).
7. The most likely reason for queue manager congestion is excessive
bounces to invalid sender addreses, that clog the smtp delivery
agent output queue, and take a long time to time out.
This could be caused missing input recipient validation, or by
misconfiguration that creates an excessive load bounces. Mail
routing loops can also contribute.
Of course misconfiguration that causes delivery agent failure
or lots of traffic to a non-working destination also "help".
8. To understand what's in your quuee, see "QSHAPE_README".
Look at both "qshape" and "qshape -s" (the latter is grouped
by sender domain).
http://www.postfix.org/QSHAPE_README.html
If that does not immediately make the problem clear, post the
output and come back and ask for help to interpret it.
9. As mentioned by others the OP will actually need to show some
logs that involve delivery agents succeeding and failing.
Restart Postfix if necessary, but capture enough logging to
show processing by one of:
smtp unix - - n - - smtp
relay unix - - n - - smtp
error unix - - n - - error
retry unix - - n - - error
discard unix - - n - - discard
local unix - n n - - local
virtual unix - n n - - virtual
lmtp unix - - n - - lmtp
which write logs tagged as "postfix/<agent-name>", where
<agent-name> is the last column above. Note that's "smtp"
not "smtpd".
--
Viktor.
