Every time I update dovecot2 with `portmaster -r`, dovecot-managesieve doesn't get dealt with as a dependency because the Makefile depends only on the dovecot port. It's got an easy workaround, but it's an annoyance regardless. I would file the patch, but I'm not sure how to do DEPENDS with either/or conditions.
for dovecot2, you need mail/dovecot2-pigeonhole. This is the SUPPORTED Sieve/ManageSieve plugin for mail/dovecot2. Larry Rosenman maintainer, mail/dovecot2-pigeonhole.
Closing since dovecot-managesieve is not supported for dovecot2, which is clearly the reason why there is no optional dovecot2 dependency. Thanks for the quick response.