I recently migrated from the trusted Courier IMAP application to Dovecot on my cPanel server.  There were several reasons for this migration, but the promise of better and more efficient resource usage was the most compelling reason to leave the familiar for the the newest thing.  WHM, made the migration both transparent to my customers as well as a breeze by not only handling the transition, but also mail format transformation for any cPanel e-mail account that required it.

Within days, the promised resource savings were realized and everything was humming along.  My customers did not even notice the middle-of-the-night migration which took approximately 5 minutes.  Outlook 2007 and 2003 as well as Thunderbird, Horde, RoundCube and Windows Mail were all happily sending and receiving without a complaint.  All was going well… or so I thought.

At first, I did not even make the connection between the Dovecot migration and erratic delivery of mail to my BlackBerry via BIS.  After all, Dovecot supported IMAP IDLE.  So, I spent several weeks suffering not getting all my messages delivered to my BlackBerry with the security that they were all still waiting for me on the server accessible through my client of choice.  My first object of blame was BIS.  So, I logged into my carrier’s BIS portal and triple checked the settings- server, check; port, check; secure connection, check.  Then, the obligatory “send Service Books.”  Next, I turned to my carrier, Verizon.  I searched the CrackBerry.com forums but could find an answer to my strange problem.  Those intermediate issues are always the most difficult to solve you know!

Then it just hit me… Dovecot must be to blame.  A quick Google search revealed that others were experiencing issues with what they referred to as Dovecot “falling asleep” and not reacting to IDLE updates with various email clients.  However, none seemed to mention the strange BlackBerry push mail issue that I was seeing.  Not being one to give in, I knew that the answer had to be out there somewhere… and it was.   I pulled up the Dovecot configuration file etc/dovecot.conf and discovered the following entry:

# When IDLE command is running, mailbox is checked once in a while to see if
# there are any new mails or other changes. This setting defines the minimum
# time in seconds to wait between those checks. Dovecot can also use dnotify,
# inotify and kqueue to find out immediately when changes occur.
#mailbox_idle_check_interval = 30

As you can see,  mailbox_idle_check_interval was commented out by default.  I uncommented that line, restarted Dovecot IMAP services and Bam! I am now getting mail within seconds of landing on the server.

Hopefully my few weeks of hair pulling puzzelment will help someone else avoid a similar expereince.