Error indexing mbox file /var/mail/user: LF not found where expected
This happens with Dovecot v0.99.x when there are multiple From-lines in row in the mbox, ie:
From some@one Wed Jan 5 09:03:48 2000 From another@one Wed Jan 5 09:09:25 2000
This shouldn't normally happen, and it's not good in any case to have them. Deleting one of them fixes the problem. Dovecot 1.0 releases don't have this problem anymore.
These are usually related to incompatible locking settings between all programs accessing the mboxes. Make sure they use the exact same locking methods.
Empty line at the beginning of mbox
This is an unsolved rarely occurring bug in 0.99.x Dovecot versions. Use 1.0 releases instead.