Controlling inactivity timeout for IMAP

I have a problem with a user who uses a wireless carrier that keeps changing his IP as he travels throughout the city. From the perspective of our dovecot IMAP server, the user keeps logging in from another IP, and after a short while, hits up against the mail_max_userip_connections limit. It takes 30 minutes before those orphaned connections times out.

Is there any way to decrease the IMAP idle timeout other than to recompile dovecot with a new value?

imap-common.h:#define CLIENT_IDLE_TIMEOUT_MSECS (60*30*1000)

For example, will this work?

service imap {
	idle_kill = 600
}

Joseph Tam jtam.home@gmail.com