New Code!
postoffice has been rolled up to version 1.3.pre3, because I've made a few modifications to the way sendmail filters are processed, I've added some sanity checking to configure.sh, and I fixed a bug with wildcard aliases inside virtual domains (* to a local user causes an alias loop, which is not what I intended.)
The new sendmail filter features are not yet documented, which is about the only thing keeping me from officially rolling up to version 1.3, but as for now 1.3.pre3 is the most up to date postoffice there is.