Turns out for Protonmail there is no limit on how much email you can receive. The 150/day limit is for sending emails, not receiving. I think it's enough for general usage. I will gradually transit some communications to PM.
Only thing is the 500MB storage limit. But for now I got the habit of delete every email I read except important ones. Emails with large attachments can also be downloaded and deleted. So it should work for at least a few years of time. Maybe after a few years they will increase the storage!
