Dovecot 0.99.10.8 installed from the ports collection on mother running OpenBSD 3.6 didn’t work for some of the Coop members, with their indices corrupting and imap processes hanging and stopping further imap processes from running properly.
Updated to the latest stable release 0.99.12.1 manually. The login processes kept dying. It just didn’t work.
Tried the latest 1.0 test release 1.0-test58. There has been no index corruptions since. Looking good.