I recommend purelymail.com (not affiliated in any way, just a happy customer).

I've been a customer for 4-5 years, ever since I saw a hn post about them, and I have zero complaints.

It's dirt cheap ($10 per year for unlimited amount of users).

They allow wildcard addresses and I've set up my own "trash mail" so I can register an account at e.g. LinkedIn with linkedin@my-domain.com.

I've set up 4 different domains and 3 accounts and all of this for $10 a year.

Sorry if this reads like an ad, but I think it's super cool to offer such a great service for a fair price.