[Users] Date incorrect in Outlook 365 IMAP append

[Claudio Passerone]

Hello,
I have a problem in using Claws Mail with Outlook 365. I used to have
my corporate email service using POP3, and was downloading messages on
my PC with Claws Mail. I have been recently migrated to Outlook 365
using the IMAP protocol. Setting up the new email was not a problem,
and I can see the subscribed folders, receive and send email. Since I
have a lot of space on the server, I wanted to replicate my large local
folders on the IMAP server. When I copy a message from a local folder to
an IMAP folder, everything looks fine in Claws Mail. However, if I
access the same folder using the Outlook Web App, the date shown for the
message is the date I copied the message, rather than the original
date. Notice that if I access the same folder using Outlook or
Thunderbird on my PC, the date shows correctly. This makes using the
Outlook Web App a pain, because all my past messages show the same date
and sorting them is impossible. Note that copying a message from an
IMAP folder to another IMAP folder preserves the correct date.

I think I found where the problem is. Outlook Web App uses the
INTERNALDATE to show the date. This parameter can be set using the IMAP
append command, however Claws Mail sends NULL as a parameter, which
tells the server to use the current date (if INTERNALDATE is not
already set, like when copying from IMAP to IMAP). This is in the file
src/etpan/imap-thread.c at line 3160:

3160         r = mailimap_uidplus_append(param->imap, param->mailbox,
3161                             param->flag_list, NULL,
3162                             data, size, &val, &uid);

The date is the fourth parameter. Is there any chance that this
parameter can be set to a meaningful value, without causing problems to
other operations? Or is there any workaround? This is the same problem
that was addressed in MailCore2 in this issue:

  https://github.com/MailCore/mailcore2/issues/715

Thanks a lot in advance for your help.

Ciao, Claudio.