[MlMt] IMAP Problem for Account

[Bill Cole]

On 2023-12-07 at 11:36:07 UTC-0500 (Thu, 07 Dec 2023 17:36:07 +0100)
Stephan Bösebeck <mailmate at lists.freron.com>
is rumored to have said:

> Then, after staring MailMate again, it was downloading everything and 
> it was _then_ fine...
>
> Until I sent an email. I got the UIDVALIDITY-Message more or less 
> directly after sending.

That is a clue that it probably was specifically and solely related to 
your "Sent" IMAP folder at that point.

The UIDVALIDITY value is an integer set by the IMAP server for each IMAP 
folder and included in the server response to an IMAP client selecting a 
folder. It is changed only when there is a change in mapping of messages 
to UID values, which are unique and notionally permanent ID numbers for 
each message for as long as it is in the folder. That can be made 
necessary by catastrophic server failure and restoration from backup or 
by anything mimicking such an event, e.g. serious sysadmin error, total 
re-indexing of mailboxes, etc. If it happens to an account, it will 
likely strike every folder in an account (and possibly every account on 
a server) at the same time, and MailMate may alert for each folder as it 
is selected for routine sync. It should absolutely NOT be a frequent 
event, because it forces a full resync of all message data and metadata 
in the folder.

One thing that could cause an apparent single-folder UIDVALIDITY change 
is if one were to delete and re-create an IMAP folder of the same name 
with one IMAP client, while other IMAP clients are offline. Hence, it is 
*possible* for such a change to indicate account compromise and an 
attempt to obfuscate the apparent history of a mail folder.

> I removed the account in total again, this time it worked... so I try 
> to add it once more...
>
> I will see, if that helps.

If it recurs, particularly for multiple IMAP folders on that account, it 
would most likely be a recurrent problem  with your IMAP server. If it 
recurs for just one folder, you may have a quiet account hijacking in 
progress. It is extremely unlikely that MailMate could have a 
client-side issue with tracking UIDVALIDITY at this point in its 
history, as it is logically quite simple to do correctly.

-- 
Bill Cole
bill at scconsult.com or billcole at apache.org
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
Not Currently Available For Hire