On 2020-03-17 13:31, Sergey wrote:
On Tuesday 17 March 2020, Andrea Venturoli wrote:
From time to time, I receive some message that are refused
and bounce. Do to possible blacklisting, I *really* want to
avoid bounces.
I use Sendmail+Cyrus a very long time and I not remember this
problem exactly. Cyrus is not receive messages in two cases:
1) message contains 8-bit symbols (not encoded to base64 or
QP) in header;
2) message contains NUL character.
The first is subject of reject8bit option in imapd.conf. About second look
to https://groups.google.com/forum/#!topic/comp.mail.sendmail/xW7S5vXDNtY
May be the first one causes the "Data format error" message.
Thanks for pointing this out!
I've been fighting the "NUL characters" problem on the sendmail side for
a long time: it seems I won about some 10 months ago, since I don't see
any more of these errors in the logs after May.
I'm still seeing bounces, but, as you say, the reason is not the same!
So, focusing on 1), I my imapd.conf I have:
# If enabled, lmtpd rejects messages with 8-bit characters in the
# headers. Otherwise, 8-bit characters are changed to `X'. (A proper
# soultion to non-ASCII characters in headers is offered by RFC 2047
# and its predecessors.)
#
#reject8bit: no
Also,
https://www.cyrusimap.org/imap/reference/manpages/configs/imapd.conf.html#std:cyrusman-imapd.conf(5),
says "reject8bit: 0" is the default.
From this I understand my setup should NOT reject 8bit headers (but
change non-ASCII characters to X).
I'm now setting this explicitly and I'll see what happens.
bye & Thanks
av.
P.S.
Assuming I now receive such messages, what about settings munge8bit: 1?
Any drawback or risk?
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