+ symbols aren't always used for aliasing though, and companies that strip them out can break the email address. There's no guarantee that dan+foo@example.com is the same person as dan@example.com.

I have a catchall domain and used to use email addresses like shopping+amazon@example.com with a Sieve rule to filter it into a "shopping" folder, but these days I just do amazon@example.com without the category or filtering.