We're running 1.1.4 in production on one machine, and have tried 1.1.5. and 1.1.6 in our test environment... all three still sometimes have the "next message unexpectedly lost" error logged. This happens only for Outlook users, and corresponds to the user seeing a message with no subject or body in Outlook's list.
I've finally managed to reproduce this with my own mails a few days ago. Now I'd just need to figure out what exactly is causing it and fix it.
Glad you were able to identify the issue. We see it every few days as well using mbox and POP3 checking where sometimes an "in the middle" deletion of a message (via a POP3 checker POPTray) will cause the empty message to appear to any POP3 check with a pop checker, pegasus mail, outlook, etc... It does not appear to be isolated to Outlook. Deleting the index files resets things.
As a followup, we just had this happen again on an mbox POP3 check. Using pine, the message appears normally. I used telnet to access the POP box through dovecot, issued a "RETR" command on the new message, and it was blank. then I issued a "RETR" command on the email before it, and again a RETR command on the "blank" email and it appeared normally from that point forward using dovecot.
Hope this helps in figuring out this issue.
Rob