[Dovecot] Mailbox isn't a valid mbox file

[Kenneth Porter]

Getting "Mailbox isn't a valid mbox file" on 1.2rc2 after transferring mail 
from an ancient 0.99.13 system. The first line of the file looks ok. 
Curiously, it's one of my archival folders of this list. Here's the first 
header from the top of the file:

>From tss at iki.fi  Sat May  1 21:48:17 2004
From: tss at iki.fi (Timo Sirainen)
Date: Sat May  1 21:54:18 2004
Subject: [Dovecot] 1.0-test2 released
Message-ID: <1083437297.21296.19.camel at hurina>
X-IMAPbase: 1085322222 20128
Status: RO
X-UID: 14065
Content-Length: 226989
X-Keywords:

It would be nice if the code that verified the mailbox format would log 
details about what it disliked.