email notification regression between 2.2 and 2.3

Hi,

Hello.

For the last year, each time i've tried updating dovecot from 2.2.x to 2.3.x, I had to rollback because of the following problem:

Users don't "see" new emails arriving in subdirs.

To be specific

• we mostly use/tested thunderbird client
• we use maildrop for delivery
• this is using imap, not pop3
• when a new email arrives, thunderbird renders the dir name in blue and appends a "(1)" (or more..). That's what we call 'see'
• this happens only on 'subdirs', not the main directory.
• the server is a typical linux amd64, using the gentoo distribution

More testing shows that that change, or at least not now/easily. Our users heavily use .mailfilter

• if we switch delivery to dovecot-lda, it works ok. But we can't commit

• if the user is currently viewing the subdir, then email notification is working
• better : if the user went on the subdir and then in another dir, it keeps on working. It seems we need to 'open' it at least once for notification to work
• "maildir_very_dirty_syncs = no" doesn't help (we had =yes)
• "mailbox_list_index = no" doesn't help
• i can confirm inotify was detected/used in autoconf when installed (anyway it works well with 2.2)

I'm always on freenode (orzel). I'll be in #dovecot the next days at least.

greetings,

Thomas Capricelli