They drop in value when used, which a lot of upper middle class are probably offloading right now.

Also you can get financing on them, and while they aren’t cheap, you can buy them for a lot less than a home.

If you have a relay or SEG it’s not to hard. Dealing with spam can be a problem.

Availability can be an issue, and creating an HA email server starts to get pricy.

There’s a reason email administration can be a full time job.