Adjusting Courier IMAP to support Thunderbird Defaults Posted by Jeff

The Courier IMAP mail server has a default limit of 4 connections per IP address. Mozilla Thunderbird defaults to using up to 5 simultaneous connections per server. This is a problem. :) Many pages document how to fix it from Thunderbird, but here's how to fix it in Courier IMAP on the server:

I'm running FreeBSD Unix. I find my courier imap configuration files in /usr/local/etc/courier-imap/

You'll find a file called imapd - edit it. There's a line that says MAXPERIP=4. Change the 4 to a 5 or a bit higher, to be on the safe side. But don't make it too high -- this restriction is there for a reason.

Now, restart courier imapd. I did this on my system by going to /usr/local/etc/rc.d/ and running:

./courier-imap-imapd.sh stop

./courier-imap-imapd.sh start

And there you have it. Your Courier will now behave gracefully with the default settings for a modern version of Mozilla Thunderbird.