So Gandi went to shit and will kill my mailboxes soon, I’ve been moving the domains to porkbun but i still need to deal with mail.
What are the very cheapo options for mail that don’t suck ass that have:

No Google
No VC money
Use your own domain (redirect OK so long as I can use a 3rd-party client to set the FROM: to my domain)
IMAP. I am not using your fucking app under any circumstances (that rules out fastmail and protonmail which you were about to suggest)
Also spam filter that works