Im not able to find a house for $5 around here… :(

Im going to use protonmail for my next domain im looking into getting (when i come up with a name for it :D)

Custom domains
sub-accounting or what its called, aliasing in email like gmail… yourname+something@mail.tld so you can tag and see where spam and such comes from (who sold/leaked your email?)

Proton mail have both imap and smtp available

No idea of anything already made, but this doesnt sound “way too hard” to code one self if you know how to program.