Re: IMAP changes timestamp when moving an article to another group

[Steinar Bang <sb@dod.no>]

>>>>> Eric Abrahamsen <eric@ericabrahamsen.net>:

> I looked at the link, but I still don't really see where he's saying
> that you can specify the INTERNALDATE.

You're right.  I misread, he says that about the APPEND command.

> The IMAP specs certainly don't indicate that any additional arguments
> are possible with a MOVE command.

No, that was mbox-specific implementation on part of dovecot: if the
move command is used, the file is just moved from one directory to the
other (ie. on a GNU/linux filesystem: the inode is untouched) and mtime
is preserved, and therefore INTERNALDATE is preserved.

However in March 2016 in the git history of nnimap.el there were some
changes where Gnus stopped using MOVE on dovecot.

> You can specify a date with APPEND, but the only time Gnus uses that
> is when replacing an article, not MOVEing (so far as I can tell)...

Yes, I saw that when I was reading the specs of COPY yesterday (after I
had posted the message you're responding to).

However dovecot could (and really should) pick the date out of the Date
field of the source message when doing a COPY and use that as the mtime
of the new mbox file. 

Currently, I'm guessing, when dovecot w/mbox does a COPY, the mtime of
the message file in the mbox folder will become time the file was
created.