Gmail Trick: Filter messages from Subscriptions

Gmail also ignores characters after the plus (+) symbol in an email address. The following email addresses go to the same Gmail inbox:

firstnamelastname@gmail.com
firstnamelastname+booklist@gmail.com
firstnamelastname+subscription@gmail.com
Knowing this can be a great way to filter messages from your subscriptions. Add a plus symbol and the name of the subscription after the first part of your email address when you sign up for a subscription.

Next, set up a filter in Gmail to send all messages with the plus symbol and the name of the subscription to a specific label (folder).

Source: https://business.tutsplus.com/articles/quick-gmail-tips-tricks-and-important-secrets--cms-28022