With Leap 42.3, Postfix was upgraded from 2.11.8 to 3.2.0.

Since this upgrade, I see mail rejects caused by SMTPUTF8, for example:

- dovecot lmtp
  (mail address and hostnames anonymized)

Mar  5 10:13:14 server postfix/lmtp[2703]: 3636F1D273DC: to=<user@example.com>,
relay=mail.example.com[private/dovecot-lmtp], delay=0.03, delays=0.03/0/0/0,
dsn=5.6.7, status=bounced (SMTPUTF8 is required, but was not offered by host
mail.example.com[private/dovecot-lmtp])

- amavis
  (mail address anonymized starting at "user=", hostnames anonymized)

Feb 15 12:38:28 server amavis[3273]: (03273-17) ESMTP: 501 5.5.4 Syntax error
in MAIL FROM parameters; smtp_resp: MAIL
FROM:<bounce+28f75a.232d6-user=example.com@mail.example2.com> BODY=8BITMIME
SMTPUTF8\r\n

So both amavis and dovecot lmtp do not understand SMTPUTF8 and reject the
mails.

"Luckily" this only affects a few mails per day, but that also means the
problem will probably stay unnoticed in most cases.


As a workaround, I set   smtputf8_enable = no

I don't have a 42.2 system anymore to check what the default was there, but my
guess is that it was set to 'no' there.

For 42.3, I'd recommend to release a postfix update that changes the default
for smtputf8_enable to 'no'.

For Tumbleweed and Leap 15, please make sure that both amavis and dovecot lmtp
understand SMTPUTF8.