I am seeing the following in the postfix logs, and we are having a delivery problem to blarg.com
. However the destination_concurrency_limit reported at 20 took my by surprise. I was under the impression we had already set it higher.
Feb 11 12:36:08 email postfix/qmgr: warning: mail for blarg.com
is using up 4001 of 4812 active queue entries
Feb 11 12:36:08 email postfix/qmgr: warning: this may slow down other mail deliveries
Feb 11 12:36:08 email postfix/qmgr: warning: you may need to increase the main.cf
smtp104_120_110_27_destination_concurrency_limit from 20
Feb 11 12:36:08 email postfix/qmgr: warning: please avoid flushing the whole queue when you have
Feb 11 12:36:08 email postfix/qmgr: warning: lots of deferred mail, that is bad for performance
Feb 11 12:36:08 email postfix/qmgr: warning: to turn off these warnings specify: qmgr_clog_warn_time = 0
We use sender dependent transport maps to allow our applications to send out the correctly plumbed sending-ip.
smtp inet n - n - - smtpd
smtp104_120_110_27 unix - - n - 150 smtp -o smtp_bind_address=184.108.40.206 -o syslog_name=postfix-app1 -o smtp_helo_name=mail-27.redacted.com
root@email:/var/log# postconf -n | grep destination_concurrency_limit
smtp_destination_concurrency_limit = 75
root@email:/var/log# postconf -d | grep destination_concurrency_limit
default_destination_concurrency_limit = 20
lmtp_destination_concurrency_limit = $default_destination_concurrency_limit
local_destination_concurrency_limit = 2
relay_destination_concurrency_limit = $default_destination_concurrency_limit
smtp_destination_concurrency_limit = $default_destination_concurrency_limit
virtual_destination_concurrency_limit = $default_destination_concurrency_limit
If I am understanding the implications correctly the currently set 'smtp_destination_concurrency_limit = 75' ONLY controls the limit for the smtp line in master.cf
; it's not an inherited default for any 'smtp' service like we had assumed.
If my intention is to increase all of the smtpYYY_YYY_YYY_YYY interfaces then I need to set 'default_destination_concurrency_limit = 20' higher. (and 75 is probably way too high)
OR create entries for the specific transports in main.cf
smtp104_120_110_27_destination_concurrency_limit = 30
I'm assuming that over time we set it higher, and not seeing a negative effect kept increasing it, but there is almost no mail that goes out the default smtp interface, so we've been effectively running at a destination_concurrency_limit of 20 this entire time on all of our custom interfaces.
I also understand raising the destination_concurrency_limit isn't going to solve the deliverability problem; it will only correct our understanding and intent regarding the configuration of our default_destination_concurrency_limit for this and other interfaces.
Is my resulting understanding correct?