[Dovecot] 1.0alpha2: how to reject specific users?

[Jeff A. Earickson]

Hi,
    In Qualcomm's qpopper, you can specify a list of users
to reject at authentication, even if they are otherwise
valid, by putting them in a file (/etc/pop.nonauth).  I
use this to occasionally ban users who bang on the system
needlessly until they Get a Clue.  I looked thru the 
wiki.dovecot.org/Authentication pages and didn't see anything
like this feature.  Does it exist in 1.0?

BTW, running 1.0alpha2 in production since Sunday night,
working great.  Zero core dumps, only minor chatter about
"Corrupted index cache file" in the syslog, no problems.

Jeff Earickson
Colby College