Resurrecting this thread -
I'm migrating to PMG from the free (but now defunct) EFA Email Filter Appliance in my home lab, and I have deployed the SpamTitan appliance at work. My hope was to also migrate work to PMG pending how well it works for me at home.
Both EFA and SpamTitan have the functionality being asked for here (both of which use postfix and spamassassin), and I'm going to say that it gets used extensively at work. In no way is a BCC inbox a substitute.
I would certainly get some pushback from my admins if I switch to PMG without the ability to download or re-release clean messages. We have other security products sitting in between our gateway and our inbox server. Troubleshooting those products without the ability to release messages exactly as they would normally be forwarded by our gateway would be a significant burden, as we would have to contact the sender to have them try again each time we made configuration changes to test. I simply cannot commandeer our customers' employees into our IT department.
There is no way to take a message from an inbox and run it back through our other tools for testing, as the headers will now contain entries for the inbox server. It is likely that DKIM and S/MIME signatures would be compromised in that process.
I hope you will reconsider implementing this feature.
Thanks.
-Ramon