[Dovecot] Couldn't init INBOX: Can't sync mailbox: Messages keep getting expunged

[Tom Sommer]

After updating Dovecot, one of my servers keep spamming these errors in 
the log:

dovecot: Nov 03 14:14:18 Error: POP3(foo at bar.com): Getting size of 
message UID=4402 failed
dovecot: Nov 03 14:14:18 Error: POP3(foo at bar.com): Getting size of 
message UID=4402 failed
dovecot: Nov 03 14:14:18 Error: POP3(foo at bar.com): Couldn't init INBOX: 
Can't sync mailbox: Messages keep getting expunged

The funny thing is the mailbox is empty, there are no mails in the 
folder that should be needed to be parsed

It was perfectly fine before I updated, and the permissions on the 
folder is correct. It only affects some mailboxes as well.

Any ideas?

// Tom