Seems 99% reasonable, but the per-message limits make it a non-starter for me. I get why they’re doing it and totally understand where they’re coming from, but the off-chance that an incoming email gets bounced due to no fault of my own (other than subscribing to a higher tier) just doesn’t work for me.
I can also vouch for Migadu. I've been using it for 6-7 years with 4 different domain names because they only charge for usage; not per domain or user. The few times when I contacted support they were also very helpful.
You pay for mailbox size and number of emails in/out. Can add as many domains/users as you like.
I use the micro tier ($20 a year), it's more than enough for me.
https://www.migadu.com/pricing/