maintainer-wanted gentoo@bitcetera.com Sven Schwyn Postwhite is a policy server for Postfix MTA which filters incoming emails based on per recipient whitelists managed by an email frontend. Incoming emails are denied unless the sender address or sender domain is present on the recipient's whitelist. This concept is neither new nor fancy in itself, but the way Postwhite lets you manage your whitelist sure is. Here is a real life example: Arthur's main email address arthur@dent.tld is great for everyday use, but he doesn't want to pollute it by using it for mailing lists, websites, online shopping and such. Postwhite to the rescue! Arthur creates a virtual email address hitchhike@dent.tld which is delivered to the same mailbox. He adds this address to recipients.yml and then restarts Postwhite. Initially, all incoming emails will be denied, so when Arthur decides to join the Betelgeuse mailing list, his whitelist has to learn about this. Arthur sends an empty email to hitchhike+learn@dent.tld which puts Postwhite into learning mode for a limited period of time. In learning mode, Postwhite allows and delivers any incoming mails, yet it delivers a followup notification message along with it. When the first email from the Betelgeuse mailing list comes in, Arthur simply replies to the corresponding notification message thus adding Betelgeuse to the whitelist.