It happened a number of times now that my inbox would shrink in message count without my explicit doing. Generally, your inbox automatically emptying should be conceived a good thing, but it isn’t always. It took me a while to put together the pieces:
- left over messages are all new or old, meaning “not read”,
- offlineimap logs suggested that I deleted those messages on one of my workstations, before offlineimap synchronised those changes to the other machines, and
- it seems to coincide with instances of use of Mozilla Thunderbird and maybe other IMAP clients.
I think I unvealed the mystery: some IMAP clients automatically mark read messages as deleted. Don’t ask me why, I did not configure it, and even though I told Thunderbird specifically not to do it, I have no other explanation than to assume that it doesn’t care about what I want, but marks them for deletion anyway. Firefox decides to block cookies several times a day, despite my explicit requests to store them, and the two are from the same project, so it seems plausible.
Once marked for deletion (by way of an IMAP flag),
offlineimap propagates the flag to all clients. Since
I set delete=yes for mutt, if I then open
and close a mailbox with such messages without noticing them, the
messages are purged.
I gave up fighting and solved the problem at a different point, namely mutt (which was doing the deleting anyway):
folder-hook . push '<undelete-pattern>~D<enter>'
Since mutt deletes mail marked for deletion when I
close a mailbox, finding those messages at time of mailbox opening
must mean that they have been marked outside of the mailer — I use
mutt for everything, exclusively. So let’s undelete
them.
I can’t see any negative consequences of the above hook.
NP: Oceansize: Efflorescence
