[Dovecot] Logging in with '+' delimiter

[Jerry]

Dovecot v1.2.4
FreeBSD-7.2

I have Postfix configured to use Virtual Users & Domains and use
Dovecot for virtual delivery. Postfix also sends, dovecot correctly
places mail with '+'addressing; i.e., "foo+bar at domain.com" into
"path-to-mail/domain.com/foo+bar". The problem is when I attempt to
access the mailbox, the user name: foo+bar at domain.com is rejected.

Is this by design, or is there a way to circumvent this problem?

-- 
Jerry
gesbbb at yahoo.com

Fortune favors the lucky.