[Dovecot] Upgrading to dovecot2 broke IDLE on one mailer, but not another

[John Stracke]

Last weekend I upgraded my server (complete reinstall, actually), from 
Debian sarge to wheezy, which brought me from dovecot 1.x (I think) to 
2.1.7.  It's all working now, *except* that the MUA I use on Android, 
Kaiten (a fork of K-9), apparently no longer gets IDLE notifications.  
Before the upgrade, when mail arrived, Kaiten would pop up an Android 
notification immediately; now, it never does (or it might, hours later, 
with all the messages it notices at that time--presumably this happens 
when its background service gets killed off and restarted).

The weird thing is that IDLE still works flawlessly with Thunderbird, 
which suggests this is a protocol interaction between Dovecot 2 and 
Kaiten.  (I plan to check with the Kaiten folks next.) Has anybody here 
seen this? Is there something I can turn on in Dovecot to help debug it?

I did check my old Dovecot settings, and they didn't specify anything 
non-default about IDLE.

Thanks in advance!

My configuration from dovecot -n:
# 2.1.7: /etc/dovecot/dovecot.conf
# OS: Linux 3.9.3-x86-linode52 i686 Debian 7.0
log_timestamp = "%Y-%m-%d %H:%M:%S "
mail_access_groups = mail
mail_location = mbox:~/mail:INBOX=/var/mail/%u
mail_privileged_group = mail
passdb {
   driver = pam
}
protocols = imap pop3
service auth {
   user = root
}
service imap-login {
   inet_listener imap {
     port = 0
   }
}
service pop3-login {
   inet_listener pop3 {
     port = 0
   }
}
ssl_cert = </etc/ssl/certs/dovecot-2009.cert
ssl_key = </etc/ssl/private/dovecot.pem
userdb {
   driver = passwd
}
protocol imap {
   mail_max_userip_connections = 100
}
protocol pop3 {
   pop3_uidl_format = %08Xu%08Xv
}

and the no-comments version of conf.d/20-imap.conf:

protocol imap {
   imap_idle_notify_interval = 10 mins
}

-- 
/==============================================================\
| John Stracke         | http://www.thibault.org | HTML OK     |
| François Thibault    |---------------------------------------|
| East Kingdom         | "Okay, one more time, with *vowels*." |
| francis at thibault.org | -- Ozy and Millie                     |
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