They will have access to metadata - otherwise they wouldn't be able to work as email service. That's sufficient to implement those protocols.
The client then would have to bring their own crypto, and you'd probably want the SMTP server to reject mails if delivered unencrypted (though their FAQ says you can send unencrypted mails).
The reason they claim they can't is probably trying to keep full control over what users are doing, in which case I agree - fuck them, don't use services like that.
There was the 386DX and significantly cheaper SX - first was full 32 bit, second just 32bit instruction set with smaller external busses.
Then you could add the math coprocessor. And of course RAM and disks were expensive. 16MB RAM was way above normal for that time.