Try Fastmail. If you want to reply you can setup a sending identity with the necessary email address. You don't have to do anything ahead of time.
I was going to, but looking at the benefit of having the rest of the Google applications and being free, I didn't.
Sweet, will check it out, I'm not particularly attached to gsuite
They also have a neat way of doing wildcard delivery if you use them for DNS: [email protected] gets translated to [email protected].
The only major issue I've had, with gsuite at least, is not being able to reply from one of the not-actually-existent addresses on my domain.