Love the conversation this has kicked off, and I think there's a few good things to consider here:
The main thing I was originally aiming at first was better visibility into the mail subsystem and second to that more control over those various components
Expanding the capability of the mail system to include additional processing by farming out additional processing to external servers like CipherMail, Proxmox, etc. could be done easily for even sparsely-resourced servers. However, optionally enabling certain processing like Antivirus on the same machine is still likely a good idea.
A lot of us are also running fairly beefy servers for large production setups and it seems disingenuous to rule out completely more resource-intensive operations from the core packaging just because some machines at the lower end couldn't support them. Making them optionally available, even subject to certain resource constraints and so on, is exactly what I'm hoping we can get to - a lot more control over the mail system so that administrators can choose how much in terms of resources to invest in that system. A combination of more inspectable, optional services available on the core offering as well as allowing external smtp-based components to slot into the workflow sounds like the best of all worlds.
