SMTPUTF8 not supported on internal ports 24 (Gromox) and 2693 (Sphinx/Archive)?

Duese6

Hi,
I’ve noticed that emails requiring SMTPUTF8 are not being delivered on our system running Gromox 3.1.28 and Sphinx (archive).
Postfix logs show the following when relaying internally to ::1:24 (Gromox) and 127.0.0.1:2693 (Sphinx/piler-smtp):

SMTPUTF8 is required, but was not offered by host

An EHLO test on port 24 also confirms that there’s no 250-SMTPUTF8 in the response.
My question: do the internal SMTP services on ports 24 (Gromox) and 2693 (Sphinx/Piler/Archive) currently not support UTF-8, or is there a configuration option missing to enable it?

Any clarification or advice would be appreciated.

Best regards.

crpb

Had one of those the other day on one system. The funny thing is that it was a message sent via Outlook to another user on this Server.

https://github.com/grommunio/gromox/issues/191

Duese6

I also tried to add some parameters here

/etc/gromox/smtp.cfg

e.g.
enable_utf8 = 1
or
smtputf8 = 1
or
utf8 = 1

but it did not work out.

morbificagent

Same here — some emails didn't arrive because of that error message.
They all have emojis in the subject line, e.g.

"Versandbestätigung 🚚 🎉"

morbificagent

/etc/postfix/main.cf:
smtputf8_enable = no

has helped here.
So it makes a "downgrade" from utf-8 and the mail is arriving

But it would be better if gromox-delivery-queue would accept utf-8

Duese6

I’m running a PMG in front of grommunio. The PMG handles all external mail and relays everything internally to grommunio (Postfix → Gromox).

In this setup, the PMG fully supports SMTPUTF8.

The problem only occurs inside the grommunio host, when Postfix tries to hand over the message to Gromox on port 24 — and Gromox doesn’t offer SMTPUTF8.

I understand that your suggested fix (smtputf8_enable = no in Postfix) would only affect the Postfix process on grommunio itself — not the PMG in front.

Just to confirm: that would stop Postfix from requiring SMTPUTF8 for the hand-off to Gromox, correct?

Because modifying the PMG is out of the question for me — it serves hundreds of clients and relays to multiple backends.

It actually only became visible in my setup because a user released a quarantined mail from PMG.

When that happened, the message bounced back to me as postmaster, since PMG re-injects the message internally (Postfix → Gromox).

In normal external delivery cases, such bounces would go back to the original sender — so I probably wouldn’t even have noticed it otherwise 😅

So the issue only surfaced because the release-from-quarantine path exposed the missing SMTPUTF8 support on the internal delivery side.

umgfoin

From Using Postfix SMTPUTF8 support:

After Postfix SMTPUTF8 support is turned on, Postfix behavior will depend on
1) whether a remote SMTP client requests SMTPUTF8 support,
2) the presence of UTF-8 content in the message envelope and headers, and
3) whether a down-stream SMTP (or LMTP) server announces SMTPUTF8 support.
When a message is received with the SMTPUTF8 request, Postfix will deliver the message to a non-SMTPUTF8 SMTP or LMTP server ONLY if:
- No message header value contains UTF-8.
- The envelope sender address contains no UTF-8,
- No envelope recipient address for that specific SMTP/LMTP delivery transaction contains UTF-8.
  NOTE: Recipients in other email delivery transactions for that same message may still contain UTF-8.
Otherwise, Postfix will return the recipient(s) for that email delivery transaction as undeliverable. The delivery status notification message will be an SMTPUTF8 message. It will therefore be subject to the same restrictions as email that is received with the SMTPUTF8 request.

Duese6

Right, I’m aware that Postfix is behaving correctly here — it’s just following the SMTPUTF8 rules.

The issue isn’t Postfix itself, but the fact that the internal Gromox listener (port 24) and the archive listener (port 2693) don’t advertise SMTPUTF8.

In setups like mine (PMG → Grommunio → Gromox), that means any internally reinjected message (for example from quarantine release) with UTF-8 in the envelope will bounce — even though everything works fine for external delivery.

So yes, it’s technically “correct behavior”, but it still leaves a gap that needs fixing on the Gromox side.

crpb

PMG → Grommunio → Gromox

No PMG/whatever necessary.
This already triggers the delivery problems:

Gromox(localhost) -> Postfix(localhost) -> Gromox(localhost)