SMTPUTF8 is required, but was not offered by host

[link2xt]

We probably should base64/quoted-printable more when the message is not encrypted: https://support.delta.chat/t/smtputf8-is-required-but-was-not-offered-by-host/2788

The servers we are testing against (more or less default Postfix setup) support SMTPUTF8. mail.sangham.net (the sender server) also offers SMTPUTF8:

220 mail.sangham.net ESMTP Postfix (Ubuntu)
EHLO u
250-mail.sangham.net
250-PIPELINING
250-SIZE 10240000
250-ETRN
250-AUTH PLAIN LOGIN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250-DSN
250 SMTPUTF8

Maybe this happens because the receiver does not support SMTPUTF8. In any case, we should probably assume it is not supported and simply encode all messages as if there is no SMTPUTF8 support anywhere.

For reference, SMTPUTF8 is specified in RFC 6531.

[hpk42]

Yes, i think without knowing that all recipient's MTAs will support SMTPUTF8 things can break -- broadcast lists are not encrypted and thus the issue is more likely to appear there. So i agree to simply encode unconditionally and ignore if servers support SMTPUTF8 unless we can ascertain it's fine for all MTAs up to the recipients.

…

On Thu, Nov 09, 2023 at 09:53 -0800, link2xt wrote: We probably should base64/quoted-printable more when the message is not encrypted: https://support.delta.chat/t/smtputf8-is-required-but-was-not-offered-by-host/2788 The servers we are testing against (more or less default Postfix setup) support SMTPUTF8. mail.sangham.net (the sender server) also offers SMTPUTF8: ``` 220 mail.sangham.net ESMTP Postfix (Ubuntu) EHLO u 250-mail.sangham.net 250-PIPELINING 250-SIZE 10240000 250-ETRN 250-AUTH PLAIN LOGIN 250-ENHANCEDSTATUSCODES 250-8BITMIME 250-DSN 250 SMTPUTF8 ``` Maybe this happens because the receiver does not support SMTPUTF8. In any case, we should probably assume it is not supported and simply encode all messages as if there is no SMTPUTF8 support anywhere. -- Reply to this email directly or view it on GitHub: #4969 You are receiving this because you are subscribed to this thread. Message ID: ***@***.***>

[link2xt]

SMTPUTF8 allows to put UTF-8 characters into email header values. I guess the error is caused by unencoded chat name in the List-ID:

deltachat-core-rust/src/mimefactory.rs

Line 601 in ab2bc3b

format!("{} <{}>", chat.name, chat.grpid),

The code adding List-ID for broadcast lists was introduced recently in
8573649
(PR #4644)