On 2022-10-01 22:59, michael.zork@feierfighter.de wrote:

Hi Zakaria,

I'm very happy about your email to the mailing list, I thought I'm alone with my problem, and it's nice to see that the problem might be a bug/problem in pigeonhole. I was not sure about it because I didn't get a technical answer from that German provider, so I didn't know it it's a bug in pigeonhole or not. I didn't have time to investigate, thanks for your time to investigate and pinpoint to the line of code where the problem might be!

Back then, a few months ago, I disabled the "Message-Id duplicate check" because of this problem.

It's just a problem of <0.001% of the emails, most systems generate valid Message-IDs. Maybe Alibaba/Aliexpress is the biggest one who generates invalid Message-Ids...

It would be awesome if you could also try to contact Alibaba/Aliexpress, and tell them the problem. Maybe they fix it if multiple people report it. But I doubt it.

Let's see what the Dovecot guys say to this problem. Maybe the best solution is to remove the invalid Message-Id before adding a new one.

Michael

Am 01-Oct-2022 18:24:05 +0200 schrieb hi@zakaria.website:

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Hi there,

I can confirm this behavior. A few months ago I introduced a milter which is checking for multiple headers when the RFC says that

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just should be one of them For example "Message-Id".

I found the described problem in an email coming from Alibaba, which had an invalid "Message-Id" header. It didn't contain an "@" sign or similar. It was RFC-invalid.

This email was sent from Alibaba to a German email provider. There was a redirect at that email provider, pointing to my mailserver.

My server rejected the email because there were 2 "Message-Id" headers: The original invalid "Message-Id" header from Alibaba, and a new "Message-Id" header from the German provider, which seems to have been added during the redirect. There were "Dovecot-sieve" headers in that mail, so my guess was that it happened because of Dovecot-sieve/pigeonhole implementation.

I contacted the email provider, asking for help. Asking if it really is a bug in pigeonhole (or maybe some other system at that

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who knows). And I contacted Alibaba, so they fix the invalid "Message-Id". I got responses from both, but until now, as far as I can see, it has not been fixed.

The best fix would be (if it really is a bug in pigeonhole), if pigeonhole fixes the problem, then it's fixed for all users of Dovecot. I guess Alibaba is not the only sender with an invalid "Message-ID" header, but that's the only one I saw.

Michael

Am 01-Oct-2022 14:00:45 +0200 schrieb sriccio@swisscenter.com:

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You wrote in the original email the message was rejected. Sorry I don't have login access to my gmail test account anymore since

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google @#$%@#$% wanted to have me add a phone number.

In my original post I said that gmail was rejecting the forwards because of duplicate headers, and that the duplicate header seems to be a Message-ID added by pigeonhole when it's "not happy" with the original mail Message-ID.

I probably failed to explain the issue clearly and sorry for

On 2022-10-01 12:49, michael.zork@feierfighter.de wrote: there provider, the that.

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Thank you anyway for trying to help :)

Hi Michael,

I just wanted to say sorry, that I sent this empty email by mistake intending nothing else.

Anyhow, thanks so much for your valuable input, it's very much appreciated.

Zakaria.

Good Morning Michael,

No problem. Although, to be clear I didnt point out anything, but its Sébastien and the credit shall go for him.

Also, by the way in EXIM MTA, there is verify syntax condition in data acl, which checks all email headers and validate that they are standards compliant and reject sending any email beforehand to your issue which has non-compliant header and offers the ability to remove such headers with condition handling e.g. if contained any Sieve header, to request removing message id headers with headers_remove and add compliant one with add_header, and I guess this will mitigate any mail service provider rejection issue.

If you are postfix user and considering switching, let me know, I might be able to help.

Zakaria.