[Dovecot] cached message size errors

[Charles Sprickman]

Hello,

We recently moved from courier to dovecot, and I'm seeing a handful
of errors that prevent people from retrieving email.

Below is a snippet of the log sequence I see when this happens:

Oct 10 13:44:24 mbox dovecot: imap(xxx at bway.net): Error: Cached message size smaller than expected (1759 < 1830)
Oct 10 13:44:24 mbox dovecot: imap(xxx at bway.net): Error: Maildir filename has wrong S value, renamed the file from /home/vpopmail/domains/bway.net/1/xxx/Maildir/cur/1381381552.91972.xena.bway.net,S=1759:2,b to /home/vpopmail/domains/bway.net/1/xxx/Maildir/cur/1381381552.91972.xena.bway.net,S=1830:2,b
Oct 10 13:44:24 mbox dovecot: imap(xxx at bway.net): Error: Corrupted index cache file /home/vpopmail/domains/bway.net/1/xxx/Maildir/dovecot.index.cache: Broken physical size for mail UID 447401
Oct 10 13:44:24 mbox dovecot: imap(xxx at bway.net): Error: read(/home/vpopmail/domains/bway.net/1/xxx/Maildir/cur/1381381552.91972.xena.bway.net,S=1759:2,b) failed: Invalid argument
Oct 10 13:44:24 mbox dovecot: imap(xxx at bway.net): Disconnected: Internal error occurred. Refer to server log for more information. [2013-10-10 13:44:24] in=784 out=3017

Basically it looks like dovecot detects a mismatch in the file size
vs.  the file size embedded in the maildir filename, tries to fix it
and then has issues reading the fixed file.  Removing the file in
question allows the user to retrieve email.  The "invalid argument"
error seems especially strange, as I'm able to view the file by hand
with no problems.

Blowing away the indexes and letting them get recreated seems to not
help at all.

This was an old vpopmail setup with both maildrop and vdelivermail
doing the final delivery both now and prior to the migration to
dovecot.

For a quick fix, is there a way to have dovecot ignore the error and
present the rest of the mailbox?

Longer term fix, I'm not even sure where to start I've used dovecot
elsewhere for quite some time (with maildirs) and I've never had an
issue like this.

'doveconf -n' below...

Thanks,

Charles
-- 
Charles Sprickman
NetEng/SysAdmin
Bway.net - New York's Best Internet www.bway.net
spork at bway.net - 212.655.9344


# 2.2.5: /usr/local/etc/dovecot/dovecot.conf
# OS: FreeBSD 8.4-RELEASE-p1 amd64
auth_default_realm = bway.net
auth_socket_path = /var/run/dovecot/auth-userdb
auth_verbose = yes
base_dir = /var/run/dovecot/
default_process_limit = 300
disable_plaintext_auth = no
first_valid_uid = 89
instance_name = dovecot1
last_valid_uid = 90
listen = 127.0.0.1,216.220.96.26,216.220.96.25
login_greeting = Dovecot ready - bway.net.
mail_plugins = " quota"
mailbox_list_index = yes
namespace inbox {
  hidden = no
  inbox = yes
  list = yes
  location =
  mailbox Drafts {
    special_use = \Drafts
  }
  mailbox Sent {
    special_use = \Sent
  }
  mailbox "Sent Messages" {
    special_use = \Sent
  }
  mailbox Spam {
    special_use = \Junk
  }
  mailbox Trash {
    special_use = \Trash
  }
  prefix = INBOX.
  separator = .
  subscriptions = yes
  type = private
}
passdb {
  args = /usr/local/etc/dovecot/dovecot-sql.conf.ext
  driver = sql
}
plugin {
  quota = maildir:User quota
  quota_rule = Inbox.Trash:storage=+100M
  quota_rule2 = Inbox.Spam:storage=+100M
}
pop3_client_workarounds = outlook-no-nuls oe-ns-eoh
pop3_uidl_format = %v-%u
protocols = imap pop3
ssl_cert = </usr/local/etc/ssl/bwaynet.pem
ssl_key = </usr/local/etc/ssl/bwaynet.key
userdb {
  args = /usr/local/etc/dovecot/dovecot-sql.conf.ext
  driver = sql
}
protocol imap {
  mail_max_userip_connections = 40
  mail_plugins = " quota imap_quota"
}
protocol pop3 {
  mail_max_userip_connections = 20
}