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

[Steinar Bang]

>>>>> Aki Tuomi <aki.tuomi at dovecot.fi>:

> On 13.09.2017 23:59, Steinar Bang wrote:

>> 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?

> It's the file ctime.

Is there a way to get the INTERNALDATE of the source message, and use
that, if both source and destination folders are maildir folders?