Sendmail+Cyrus IMAP "Data format error" and bounces

[Sergey]

On Friday 27 March 2020, you wrote:

> With "reject8bit: yes", sendmail refuses the message with "Message 
> contains non-ASCII characters in headers". (Still don't know why it 
> doesn't refuse it upfront, but bounces it!).

This is LMTP error between Sendmail and Cyrus. The message already
received by Sendmail and Sendmail must send a bounce at this case.

I use "reject8bit: 0" and "munge8bit: 0" in imapd.conf.

> With "reject8bit: no", I get the message and the subject is translated 
> to "ProvaXX", as I would expect, since rfc2047_utf8 is, by default, off.
> 
> Strangely, if I enable rfc2047_utf8, I still get "ProvaXX" as a subject.

https://www.cyrusimap.org/imap/reference/manpages/configs/imapd.conf.html

| munge8bit: 1
|
| If enabled, lmtpd munges messages with 8-bit characters in the headers.
| The 8-bit characters are changed to `X’. If reject8bit is enabled, 
| setting munge8bit has no effect.

-- 
Regards, Sergey