dovecot - Oct 2022 - Pigeonhole redirect is adding a message-id header when it already exists

Hello,

We are using sieve filter to redirect incoming mails to an external mailbox
(gmail) an we are seeing some forwarded e-mails being rejected by gmail because
of duplicate headers.

I think was able to identify the probable cause of the duplicate headers:
It seems that when the original message's "Message-ID" is not
compliant, pigeonhole acts like if the header is not existing and adds it's
own Message-ID.

This result in having two "Message-ID" headers being submitted to the
destination mail server.

Original Message-ID:
Message-ID:
1883biz_pay_after_purchase:0:0_572392900$ae7ed6e4d53b424c84aaf83b30c507e7

Pigeon hole adds his own Message-ID:
Message-ID: <dovecot-sieve-1664386049-21512-0 at 510faa1ff2d9>

Gmail answer:
  550-5.7.1 [94.103.100.17]  Our system has detected that this message is not
RFC
  550-5.7.1 5322 compliant: duplicate headers. To reduce the amount of spam sent
  550-5.7.1 to Gmail, this message has been blocked. Please review
  550 5.7.1  RFC 5322 specifications for more information.

While I understand the original "Message-ID" seems to be all but
compliant with RFCs, shouldn't a "Message-ID" be added only when
"Message-ID" is really missing ?
When redirecting a message, If the original "Message-ID" exists but is
bogus shouldn't it still be forwarded untouched ?

Also, maybe if pigeonhole is adding it's own "Message-ID",
shouldn't it remove any previous "Message-ID" to avoid generating
duplicate headers ? (but maybe it could break some DKIM stuff?)

Any ideas how to workaround this issue ?

Thanks a lot for your feedbacks!

S?bastien RICCIO
SYSTEM ADMINISTRATOR
P  +41 840 888 888
F  +41 840 888 000
M sriccio at swisscenter.com<mailto:sriccio at swisscenter.com>

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> 
> 
> We are using sieve filter to redirect incoming mails to an external
> mailbox (gmail) an we are seeing some forwarded e-mails being rejected
> by gmail because of duplicate headers.
> 
How are you redirecting, like this[1]? I tested this ages ago. I am mostly
testing with own gmail account, so  can't imagine this not working. It was
an older 2.2 server I was testing this on.


[1]
if false # true
{
     redirect :copy "shit at gmail.com";
}