Doveadm fetch slow and 100%CPU with a specific message-id

[Ron Garret]

On Oct 25, 2021, at 4:10 PM, Joseph Tam <jtam.home at gmail.com> wrote:

> On Mon, 25 Oct 2021, Ron Garret wrote:
> 
>>>> Note that message-ids are not guaranteed to be unique.  During my test
>>>> I found groups of as many as 20 different messages with the same
>>>> message ID.  (Turns out this makes quite a reliable spam signal!)
>>> 
>>> It's by far not a rare situation: duplicate message-ids happen whenever
>>> the sender names more than one local recipient during SMTP.  It's a wholly
>>> unreliable way to indicates spaminess.  However, if a high proportion
>>> of those recipients do not exist, ...
>> 
>> I think you may have misunderstood.  What you say isn?t wrong, but in
>> the case of multiple local SMTP recipients, all of the duplicate
>> messages will have the same content.  What I have found is the same
>> message ID in messages with (very) *different* content (and often sent
>> to the same user).  All of that has been spam (and it is hard to
>> imagine any situation in which it would not be).
> 
> Ah, that is a different situation.  It could happen if the same message
> tooks different paths to your user e.g. via mailing list processor,
> but that is less common and would probably break DKIM.

I see I still haven’t made myself clear.  I’m talking about messages with the same message ID with *radically* different content.  Different subject lines.  Different senders.  Different lengths.  Different MIME message structures.  All with the same message-id and all sent to the same user.

rg