I have a Dovecot server v2.0 (from Ubuntu 12.04) and Roundcube running on the same server.
The setup generally works well, except that certain IMAP subscriptions disappear after a random time (between 10 mins - 2 hours). Only certain subscriptions go missing, other folders seem fine.
Below is a copy of my subscriptions folder:
cat /var/spool/mail/dave/Maildir/subscriptions NeedsAttention.NewDev_Dec2012 NeedsAttention.YYYYYY NeedsAttention.XXXXXX Sent INBOX NeedsAttention.Toastmasters Archive12.Postgres Archive12 Drafts
The Archive12 & Archive12.Postgres folders routinely disappear. If I cat the file again, the entries are gone. I can add them back, but then they will vanish again after a time. I used to get a similar problem with Thunderbird, but I changed the settings to show all folders.
I have stopped using TB due to the outstanding bug of ongoing network traffic with IMAP folders, so that isn't messing around with my subscriptions.
Any insight as to the cause, or at least a step to tell me what is changing that file would be greatly appreciated.