https://bugs.exim.org/show_bug.cgi?id=1874
Bug ID: 1874
Summary: Exim 4.87 silently losing email to our local mail
stores (failing to retry lmtp deliveries)
Product: Exim
Version: 4.87
Hardware: x86
OS: Linux
Status: NEW
Severity: bug
Priority: medium
Component: Delivery in general
Assignee: nigel@???
Reporter: dpc22@???
CC: exim-dev@???
Created attachment 917
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https://bugs.exim.org/attachment.cgi?id=917&action=edit
Log entries demonstrating lost email.
I upgraded Exim on our central mail hubs from a snapshot of
https://github.com/Exim/exim.git which was deployed by my colleague Tony Finch
on 24/08/2015 (which he tagged "4.86_36-e07b163") to the latest stable version,
Exim 4.87, on 03/08/2016. No change in configuration.
9 days later we received a report that email was no longer being delivered
consistently to all members of a given mailing list. Investigation revealed
that a small fraction of our local email was losing recipients. 911 messages
were affected over a 9 day period.
On Saturday I reverted back to "4.86_36-e07b163", again no change in
configuration. The problem vanished.
The root cause appears to be a serialize_hosts limit that we place on LMTP
delivery to our Cyrus mailstores in order to spread out load:
hermes_lmtp:
driver = smtp
protocol = lmtp
gethostbyname = true
rcpt_include_affixes = true
serialize_hosts = *
address_retry_include_sender = false
As a specific example, the following delivery attempt was not retried:
2016-08-12 03:25:09 +0100 1bY29l-0007xg-QF
== fanf2@??? <fanf2@???> R=hermes_lmtp T=hermes_lmtp
defer (-53): connection limit reached for all hosts
I attach the complete Exim logs for that message. Observe that the message is
only delivered to one of four recipients and then completes immediately without
any retry attempt.
I am not sure if this is related to bug 1788:
Some deliveries not re-attempted after 'T=remote_smtp defer (-53):
retry time not reached for any host' on first delivery attempt
"connection limit reached" feels different from "retry time not reached". I
will let you decide if the two bugs should be merged.
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