:-(
On 10/18/26 15:34, Viktor Dukhovni via Postfix-users wrote:
On Sun, Oct 18, 2026 at 03:09:36PM +0200, Danjel Jungersen via Postfix-users
wrote:
The remote user did reply, but the incoming mail was not delivered.
2026-10-12T18:40:50.760730+02:00 mail postfix/lmtp[116517]:
EFCA110E01DB: to=<[email protected]>,
relay=mail.jungersen.dk[private/dovecot-lmtp], delay=1.8,
delays=1.7/0.07/0.09/0, dsn=5.6.7, status=bounced
(SMTPUTF8 is required, but was not offered by host
mail.jungersen.dk[private/dovecot-lmtp])
As I read this, the remote serve requires utf8, but also uses the
alternative utf8-free address.
Not the remote server, rather your Dovecot LMTP service listening on a
unix-domain socket. You need to enable SMTPUTF8 support in the dovecot
LMTP service.
My friendly AI suggests:
Historical Context vs. Modern Support
Historically (Dovecot v2.3 and earlier):
Dovecot did not support SMTPUTF8 in its LMTP implementation.
Administrators integrating Postfix with Dovecot LMTP were
routinely advised to set smtputf8_enable = no in Postfix to
prevent delivery failures when emails contained non-ASCII
characters or emojis.
Modern Dovecot (v2.4+):
Dovecot introduced experimental support for mail UTF-8 extensions,
which brings SMTPUTF8 support to LMTP (alongside Submission and
IMAP).
Bummer
Running debian bookworm, which have dovecot 2.3.19.
Thank you for pointing this out, I will look into options for upgrading.
I have read that there are a couple of issues that make it hard to do an
upgrade, a migration is needed (or at least advised).
I believe it was dovecot that changed the way of working.
Any comments on upgrading?
Debian, Postfix, mariadb, dovecot, rspamd, clamav....
THX
Danjel
How to Enable It
To use SMTPUTF8 with Dovecot LMTP, ensure the following requirements are
met:
1. Dovecot must be built with the `--enable-experimental-mail-utf8`
configure flag (pre-built community packages often have this enabled
by default).
2. You must explicitly enable the setting in your Dovecot configuration:
mail_utf8_extensions = yes
Setting this option to `yes` enables SMTPUTF8 handling for LMTP and
Submission sessions, and `UTF8=ACCEPT` for IMAP sessions.
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