failed: Cached message size smaller than expected

[Aki Tuomi]

> On 17/04/2021 23:07 Michael Grant <mgrant at grant.org> wrote:
> 
>  
> On Fri, Apr 02, 2021 at 04:45:36PM -0400, Michael Grant wrote:
> > Every few days, my mailbox seizes up.  No mail come in to my imap clients.
> > 
> > I'm getting these errors over and over with my mailbox:
> > 
> >   Error: Mailbox INBOX: Deleting corrupted cache record uid=371208: UID 371208: Broken physical size in mailbox INBOX: read(/var/mail/mgrant) failed: Cached message size smaller than expected (17212 < 17222, box=INBOX, UID=371208)
> >   Error: Mailbox INBOX: UID=371208: read(/var/mail/mgrant) failed: Cached message size smaller than expected (17212 < 17222, box=INBOX, UID=371208) (FETCH BODY[])
> >   Error: Mailbox INBOX: Deleting corrupted cache record uid=371203: UID 371203: Broken physical size in mailbox INBOX: read(/var/mail/mgrant) failed: Cached message size smaller than expected (3904 < 3914, box=INBOX, UID=371203)
> >   Error: Mailbox INBOX: UID=371203: read(/var/mail/mgrant) failed: Cached message size smaller than expected (3904 < 3914, box=INBOX, UID=371203) (FETCH BODY[])
> > 
> > My inbox is an mbox file.  I'm running dovecot installed on Debian
> > Bullseye, the dovecot packages are all: 1:2.3.13+dfsg1-1
> > 
> > I am running sendmail and using procmail for local delivery.
> > 
> > I suspect, but am not certain, that this may be some locking issue
> > between procmail and dovecot but I have never been able to prove
> > that. The final procmail rule which appends messages to my mailbox
> > looks like this, the trailing ':' causes procmail to use a lockfile:
> > 
> > :0:
> > /var/mail/mgrant
> > 
> > The locking config lines in 10-mail.conf are commented, but I have
> > also tried uncommenting them, did not help:
> > 
> > #mbox_read_locks = fcntl
> > #mbox_write_locks = fcntl dotlock
> > 
> > Though sometimes it seems to fix itself after a few hours, the only
> > way I have found to fix this quickly is to manually remove the cache
> > files and restart dovecot:
> > 
> > rm ~/mail/.imap/INBOX/*
> > systemctl restart dovecot
> > 
> > I am not even sure this is a locking issue.  Something definitely gets
> > corrupted though. I do have several IMAP clients hitting the same
> > mailbox (phone, laptop, desktop).  On the phone, I run K9 and also the
> > gmail client which talks imap.  Also using thunderbird, outlook, and
> > w10 mail, though typically not all at the same time.  You could
> > definitely say I am stress testing this setup a bit!
> > 
> > Any ideas on how to resolve this?
> 
> I still see this corruption every day or so.  Anyone have any ideas how to debug this or resolve it?
> 
> Michael Grant

Hi!

We don't really fix issues with mbox files anymore, other than read issues.. Our focus is enabling people to move to other formats, such as maildir. I would strongly recommend you to consider using maildir instead of mbox.

I would also recommend you use dovecot-lda in procmail to deliver mail, if you are not already doing so.

Aki