TL;DR: See Summing up
!
I regularly also get emails with UTF-8
chars in the Subject:
line. Never so far any within other headers.
While a 'soft-fail'-mode in postfix is unknown to me, you may setup another smtp transport and filtering bounces through it as a kind of failsafe-mode. However, I would have yet to complete this setup myself. As of now, the bounces are sticking to the queue as undeliverable until expiry. At least they don't just get returned back to sender and I've got an eye on the sticky members of the queue. On the other hand, I am reluctant to go down further that road, now that the following method works for me(tm):
The working solution (in the case of UTF-8
chars in Subject:
only) was to just disable postfix' smtputf8_enable
feature which is nowadays defaulting to "yes" (using an up-to-date debian, that is). In main.cf add:
smtputf8_enable = no
Fiddling about with smtputf8_autodetect_classes
was inconclusive.
The email msgs featuring the UTF-8
Subject:
line are now being processed by postfix and saved by dovecot without any problems.
The solution might look counterintuitive, especially regarding the slighty awkwardly-worded postfix documentation (as you already mentioned).
The latest update about SMTPUTF8
support in dovecot seems to be the one you are referencing. Some place else I recall seeing a post the SMTPUTF8
in dovecot won't be implemented anytime soon if at all [citation needed]. Not sure whether this was an authoritative statement or not.
Another comment about dovecot and SMTPUTF8
can be found here (including your reference and this SE question): https://dovecot.org/list/dovecot/2016-November/106029.html
Together with this next post it seems the topic stalled at roughly end of 2016: https://dovecot.org/list/dovecot/2016-September/105474.html
Summing up: today, if you don't need SMTPUTF8
support in headers other than the Subject:
header, you might get away with just disabling smtputf8_enable
in postfix' main.cf and be happy as-is.
HTH
Best Answer
The message you posted says the
Mail Delivery Status Report will be mailed to <root>
.I would check the root user's mail which by default should be
/var/spool/mail/root
.