[throwaway984393]

I've been trying to use the "+" alias whenever I sign up for literally anything. At least half of the e-mail validation methods out there have no idea that "+" is a valid character. Quite annoying. Luckily I use a custom domain and everything at that domain forwards to my one user account, so I just use a new email name for fields that don't support "+".

Fastmail has a feature to automatically sort mail with a "+" into a dedicated folder, so you only need to add filter rules for those addresses that don't support the "+" character.

You still can't ignore the filtered folders, though, as sometimes you'll receive a notification out of the blue from a service or a person that is time-sensitive. So I went back to one giant inbox and I now sort mail that doesn't have a "+" sign into a dedicated "Personal" folder. Have a few more filters for jobs, receipts, and other emails that will reliably generate mail I don't ever need to read.