[Dovecot] Broken physical size caching in Dovecot 2.1.10

[Timo Sirainen]

On Tue, 2013-01-29 at 19:58 +0000, Rob Redpath wrote:

> I'm encountering two, probably related, errors in my Dovecot 2.1.10
> install. The issue relates to compressed email stored in Maildir format
> directories.
> 
> In some cases, a mailbox will become inaccessible, and the following
> will be logged from a doveadm fetch:-
> 
> doveadm(info at example.com): Error: Corrupted index cache file
> /var/spool/virtual_mail/info_example.com_d/dovecot.index.cache: Broken
> physical size for mail UID 2777
> doveadm(info at example.com): Error: Cached message size smaller than
> expected (18996 < 64624)
> doveadm(info at example.com): Error: Maildir filename has wrong S value,
> renamed the file from
> /var/spool/virtual_mail/info_example.com_d/cur/1277451630.H877760P14612.mailserver.example.com,S=18996:2,Z
> to
> /var/spool/virtual_mail/info_example.com_d/cur/1277451630.H877760P14612.mailserver.example.com,S=18996:2,Z
> 
> Interestingly, the file mentioned in the error (
> /var/spool/virtual_mail/info_example.com_d/dovecot.index.cache ) doesn't
> exist.
> 
> The uncompressed size of the file is 64624 bytes, the compressed size is
> 18996.

Dovecot's zlib plugin requires that the maildir filenames
have ,S=uncompressed size. Otherwise you get those errors.
http://dovecot.org/tools/maildir-size-check.sh can be used to fix the
filenames.