Fastmail makes it very easy (unlike many others) to send emails from any *@yourdomain.com email as a sender. But if you only need to receive email, then almost

Fastmail makes it very easy (unlike many others) to send emails from any *@yourdomain.com email as a sender. But if you only need to receive email, then almost any paid email service I know supports such catch-all addresses, even gmail/gsuite, there's no lock in.