I do not use catch-all addresses, but use a version of [domain]@mydomain.com buy adding new email addresses (aliases) in an automated way. I "remember" the used email addresses in two ways: 1) my mail server configuration contains a list of all aliases created in the past, 2) my password manager saves logins on top of that. The nice side effect is, that you keep track of all the sites you have ever created logins at.