There are tips out there on how to set up a catch all account to accept mail that wasn't addressed to any known user. That is a (very) small part of your project. When you have a catch all, nothing bounces IF the email at least when to your FQDN.
In your project, it would be a service to rate the RBLs, though in your setup you couldn't detect false positives. Maybe you should have one authorized user? Perhaps have two setups with at least on having a legitimate user plus catch-all and no open relay. That is, something close to a normal setup in addition to your accept anything server. You really can't rate RBLs in a normal setup since if one rejects the email, the others don't get a try. I have been changing the order that the RBLs appear in the configuration file with the assumption that the are used sequentially. I am working on a log filtering script to determine which catches the most spammers, though as I said, the approach is flawed since not all RBLs get a fair shot. I put the better known RBLs like Baracuda at the bottom in the configuration file. Original Message From: Glenn Forbes Fleming Larratt Sent: Wednesday, October 12, 2016 12:26 PM To: email@example.com Subject: PostFix as a "/dev/null" MTA? Folks, I've done some searching of the list archives and the web, but I can't lay hands on an answer to this question: - is there a way, ideally documented in a HOWTO or guide, to configure PostFix such that: - it will accept any mail (think "open relay", but...); - it will *never* attempt to forward that mail; - it will *never* generate e-mail: no sent mail, no return receipts, no bounces, nothing? The application we have in mind is a "Phish Phillet" engine, that would accept any mail sent to it, save the message locally, and process it using a home-grown set of analysis tools - DNS and whois queries, reputational databases, etc. - to rate messages and accumulate statistics about bad-actor mail senders and phishing sites. Thanks! -- Glenn Forbes Fleming Larratt Cornell University IT Security Office