What INTERNALDATE does dovecot with mbox storage set on a COPY'd message?

[Aki Tuomi]

On 13.09.2017 23:59, Steinar Bang wrote:
>>>>>> Aki Tuomi <aki.tuomi at dovecot.fi>:
>> On 09.09.2017 12:33, Steinar Bang wrote:
>>> When a message is copied to a folder on dovecot with mbox storage, is
>>> the mtime of the saved mbox file set to the time of the save?  
> [snip!]
>> Internaldate is picked from the separating 'From' line in mbox file.
>> "From user at example.org Thu Oct 20 18:44:06 2016"
> Sorry! I mistyped: I meant maildir, not mbox.
>
> So, to repeat the question:
>
> When a message is copied to a folder on dovecot with maildir storage, is
> the mtime of the saved maildir file set to the time of the save?
>
> Or is the mtime set to the Date: field of the source message that is
> saved?
>
> If there is a difference in the behaviour, do someone know the dovecot
> version number where the change happened?
>
> The reason I'm asking is a problem reported on the Gnus imap client in
> August 2016, where messaged moved by Gnus showed up with the wrong order
> and/or wrong date in other imap clients.
>
> (The reason for the different message ordering was that the other clients
> use the INTERNALDATE and that was changed to the time of message move
> when Gnus was used. Gnus use the Date of the source message)
It's the file ctime.

Aki