maildrop and userdb

[kang]

hi
i use qmail+maildrop+courier imap
i use userdb to setup accounts, courier imap and qmail work fine but maildrop is not able to use /etc/userdb,as it looks for it in /etc/maildrop/userdb (!)
default gentoo behavior would have been to use /etc/userdb (default compilation of maildrop seem to be /etc/userdb too)
i can symlink /etc/userdb to /etc/maildrop and maildrop recognise recipients *but* for an unknown reason, this only works manually (maildrop -d myvirtual-domain-whatever-user) it doesn't while piped by qmail (invalid recipient)

help:)