TheHolm

Nothing can beat bhyve for PFSence.

I do not understand why everyone calling hosting email difficult? IT is like 5 RFC you need to read and implement. Sofware wise you will need mail agent, something for DKIM ( if it not build in in agent), "local delivery agent" ( probably presenting it as IMAP) + mail reader of your choice. Nothing too complex

Do not try to host outbound mail on residential IP blocks, delivery will be really bad. Cheap VPS is same story. You best bet is VPS from some not well know provider, they may be avoid to be in blacklist in M$ and Google. Inbound mail is fine anywhere as so long as you can have port 25 open. DDNS works too.

Just weight your risks. Old drives can fail early, and enterprise drives consume more power. Old drives probably not for mirrors or RAID5. RAID6 and spare HDD on shelf may save your data one day. It is a lottery.

Specks lookg good, Intel NIC, semi decent CPU. I would say it is even overspec for a router.

It is an option. But used from Ali? I'm not sure that I would trust them with my data.

Thank you. Intel now offer ECC on top processors like i7 and i9. It is a news development. Now biggest problem is to find motherboard supporting ECC.

could you please elaborate? what is SFF hardware?

Try other container technologies lie LXC or go right side and play with FreeBSD jails. Quality of dockers you can find around is horrendous, giving that Docker itself build for convenience not security. It is not something I will trust.

Symphonium is another good mobile client.