Comment by drnick1

I use unique emails for every sender.

One thing I noticed is that most mailing lists now have a header that identifies them with a specific ID. When I click "Make rule from this email" in Fastmail the primary option is to sort it by that header, not by the sender or receiver. That way only the marketing emails get redirected and not transactional ones from the same sender.

List-Id: A Structured Field and Namespace for the Identification of Mailing Lists

https://www.ietf.org/rfc/rfc2919.txt

Some providers simply straight up refuse +ed aliases. I really like how gmail breaks RFC by using dots at any arbitrary position of your username. This is not at all an efficient and correct use of aliases but it gets the job done sometimes

A reasonable alternative, if you value deliverability and don't want the actual hassle of maintaining a mail server, choose a mail provider, like mailbox.org, that allows bringing your own domain.