[Dovecot] VZW Blackberry BIS problems?

[B. Cook]

Ever since Columbus day things have been strange with my two dovecot 
servers, according to my Blackberry users.

We do not have a BES just the standard BIS that comes with a personal 
account.

Several people have told me that since that Monday that they get 
occasional duplicate copies of messages which only appear singularly in 
their Maildir inboxes.

I myself even called VZW and got transferred to RIM themselves where 
they 'reset' my account; (same as me going into the BIS server and 
deleting and adding again) only to have the same thing happen; again 
occasionally..

Below is relevant dovecot info..

-r-xr-xr-x  1 root  wheel  164064 Oct  1 17:16 /usr/local/sbin/dovecot

(date it was built; prior to any problems.. *whew*) ;)

      1	# 1.2.4: /usr/local/etc/dovecot.conf
      2	# OS: FreeBSD 7.2-RELEASE-p3 i386
      3	ssl_cert_file: 
/usr/local/etc/lighttpd/ssl/mail.poughkeepsieschools.org.pem
      4	ssl_key_file: 
/usr/local/etc/lighttpd/ssl/mail.poughkeepsieschools.org.pem
      5	disable_plaintext_auth: no
      6	verbose_ssl: yes
      7	login_dir: /var/run/dovecot/login
      8	login_executable: /usr/local/libexec/dovecot/imap-login
      9	login_greeting: mail.poughkeepsieschools.org OK
     10	first_valid_uid: 89
     11	last_valid_uid: 89
     12	first_valid_gid: 89
     13	last_valid_gid: 89
     14	maildir_copy_preserve_filename: yes
     15	mail_plugins: quota imap_quota
     16	imap_client_workarounds: delay-newmail outlook-idle 
tb-extra-mailbox-sep
     17	auth default:
     18	  mechanisms: plain login
     19	  user: vpopmail
     20	  passdb:
     21	    driver: vpopmail
     22	  userdb:
     23	    driver: vpopmail
     24	  socket:
     25	    type: listen
     26	    client:
     27	      path: /var/run/dovecot/auth-client
     28	      mode: 438
     29	plugin:
     30	  quota: maildir:User quota
     31	  expire: Trash 7 Spam 30

Now what does not show here is something that I put in that it looked 
like it was supposed to help but didn't..

mailbox_idle_check_interval = 30

after looking around at other people complaining about BIS and possible 
dovecot issues it seemed that that entry was the 'magic' the BIS was 
missing; except I never had it and never had troubles.

I'm assuming this is a BIS issue of some sort, but I can't tell.

After looking on the wiki I didn't see anything that says "BIS users 
look here for tips.. "

So I'm assuming there aren't any; I think it should just work with the 
IMAP server..

Any help would be appreciated as everyone thinks this is 'our problem' 
and "if we had an exchange server we wouldn't be having these problems.."

Thanks in advance..