Why dont you use their masked/alternate addresses. That was one of the primary selling points for me. Any questionable site/service gets its own address and is easily removed or filtered if spam starts showing up.
(By the way, in GMail you can move emails to "promotional" and "social" folders, and then GMail automatically does that for you for future emails; this is quite handy, but after migrating to Fastmail this is leaving me with quite a mess in my Inbox, since Fastmail doesn't have this option).
It's not quite as elegant, but you can create a rule from an existing email in the mail options. It will try to guess at the best set of filters to match that type of email (and obviously you can refine that manually if needed), so you can send those types of mails to a Marketing folder.
For better or worse if you want to reliably control who you receive email from you need to control who knows your email addresses and have the ability to disable/filter them.