Re: [Evolution] Interaction with ProtonMail “Error syncing changes: mailbox 4 does not exist”

[Milan Crha <mcrha redhat com>]

On Wed, 2020-05-27 at 13:56 +0200, Dan Kortschak wrote:
> [imapx:A] I/O: 'A00226 SELECT Spam'
> [imapx:A] I/O: '* OK [UIDNEXT 14] Predicted next UID'
> [imapx:A] I/O: '* OK [UIDVALIDITY 4] UIDs valid'
> [imapx:A] I/O: '* FLAGS ()'
> [imapx:A] I/O: '* OK [PERMANENTFLAGS (\Seen \SEEN \Flagged \FLAGGED
> \Deleted \DELETED \Draft \DRAFT $junk junk nonjunk)] Flags
> permitted.'
> [imapx:A] I/O: '* 3 EXISTS'
> [imapx:A] I/O: '* 0 RECENT'
> [imapx:A] I/O: '* OK [UNSEEN 1] '
> [imapx:A] I/O: 'A00226 OK [READ-WRITE] SELECT completed'
> ...
> [imapx:A] I/O: 'A00237 UID MOVE 3647 Spam'
> [imapx:A] I/O: '* 3182 FETCH (FLAGS ($junk junk) UID 3647)'
> [imapx:A] I/O: '* 3183 EXISTS'
> [imapx:A] I/O: '* OK [UNSEEN 4] '
> [imapx:A] I/O: 'A00237 NO Label does not exist'

        Hi,
the above shows that the 'Spam' folder can be selected, but one cannot
move messages into it. Is it auto-populated by the server with the Junk
flag? Maybe it is a server-side virtual folder.

> [imapx:A] I/O: 'A00270 UID MOVE 13 Trash'
> [imapx:A] I/O: '* 3 EXPUNGE'
> [imapx:A] I/O: 'A00270 OK [COPYUID 4 13 453] COPY completed'

This successfully moves a message to Trash folder on connect 'A'.
Meanwhile had been made connection 'B' (and 'C').

> [imapx:B] I/O: 'B00271 SELECT Trash'
> [imapx:B] I/O: '* 3182 FETCH (FLAGS (\Seen nonjunk) UID 3647)'
> [imapx:B] I/O: '* 3183 EXISTS'
> [imapx:B] I/O: '* OK [UNSEEN 3] '
> [imapx:B] I/O: '* OK [UNSEEN 0] '
> [imapx:B] I/O: '* OK [UIDNEXT 454] Predicted next UID'
> [imapx:B] I/O: '* OK [UIDVALIDITY 4] UIDs valid'
> [imapx:B] I/O: '* FLAGS ()'
> [imapx:B] I/O: '* OK [PERMANENTFLAGS (\Seen \SEEN \Flagged \FLAGGED
> \Deleted \DELETED \Draft \DRAFT $junk junk nonjunk)] Flags
> permitted.'
> [imapx:B] I/O: '* 1 EXISTS'
> [imapx:B] I/O: '* 0 RECENT'
> [imapx:B] I/O: 'B00271 OK [READ-WRITE] SELECT completed'

The connection 'B' has selected the Trash folder now.

> [imapx:B] I/O: 'B00278 UID STORE 453 -FLAGS.SILENT (\DELETED)'
> [imapx:B] I/O: 'B00278 OK UID STORE completed'
> [imapx:B] I/O: 'B00280 UID STORE 453 -FLAGS.SILENT (JUNK)'
> [imapx:B] I/O: 'B00280 NO mailbox 4 does not exist'

IMAPx wants to unset \Deleted and Junk flags on the just moved message,
because it's in the Trash folder, where the \Deleted flag doesn't make
much sense. It succeeded with the \Deleted flag, but failed with the
Junk flag.

It seems to me that the server treats the Spam and Trash folders very
specifically, the same as the Junk flag. Why it errors out this way
might be a question for them.

With respect of the real versus virtual Trash/Junk folders, unless the
server forces subscription of these folders you can check "Show only
subscribed folders" option in the account Properties->Receiving Options
tab (which is unchecked by default), and it'll show you only subscribed
folders. Which they are can be seen in Folder->Subscriptions for that
account.

I didn't get whether using virtual trash/junk behaves properly for the
Trash/Spam sever-side folders or not. If it does weird things, then
rather stay with the real folders. I'd definitely try to contact them
and ask them about these errors. Feel free to use my text from above,
which may or may not help them from the technical point of view.

Maybe there are IMAP clients not showing these errors, but I'd be
afraid that such clients just hide these errors from the user,
pretending everything worked fine. Of course, I cannot tell for sure
unless having similar communication log. There's always a chance that
the IMAPx provide does something wrong.

        Bye,
        Milan

P.S.: by the way, you can Reply to List (Ctrl+L in Evolution), instead
of Reply to All, the same as I do here, which works better for me.