Not sure if this is more of a courier-imap issue, or a vmailmgr issue, but...
The new courier-imap 4.xx packages will not sure auth_vmailmgr provided by the vmailmgr package.
(While vmailmgr is admittedly ancient and no longer maintained, I know of no security problems with it, nor have I found an adequate replacement, and it is _still_in_portage_, so should remain supported or be removed).
Steps to Reproduce:
*** Bug 82761 has been marked as a duplicate of this bug. ***
taking over of vmailmgr bugs, being primary maintainer 'n stuff
Cool. Hopefully something will happen with this ticket. :)
Just to restate the problem (since reading over, I made a few typo's which makes the situation unclear):
The vmailmgr package provides a program called authvmailmgr which can be used to authenticate against vmailmgr virtual users/domains in roughly the same way the authpam or authdaemon programs that accompany courier-imap work. That's fine for courier 3.x, but 4.x uses a new system for plugging in authentication modules. Vmailmgr is, as far as I know, unmaintained and without a new auth module. It's a bit of a shame, since I like the way vmailmgr works better than alternatives like vpopmail, but such is life.
a) the gentoo team can continue to support vmailmgr, upgraind it's authentication modules, or
b) vmailmgr can block courier >3.x and courier 3.x can be supported for a while to give anyone using vmailmgr time to migrate to another solution.
I will try to fix this in the upcoming -r3
I'm sorry but is way too much work. I suggest to either:
a) change imap server. (suggestion: bincimap)
b) migrate to vpopmail (not something you could do easily; also, a bit hazardous from security point of view)
I've switched to bincimap which is really awesome because use the exact authentication as qmail-pop3d (I use a customized checkpassword so you can guess why I'm so excited about it). It seems to be faster than courier but it has one minor step back: it doesn't support shared folders.
Anyway, if you find a better solution than mine, just let me know.