If you even wanted to automatically assign email filters in Gmail, here is “how you can do this on the fly? The Modern Day Alchemist, aka Super Gmailer, shows us how:
For e.g. your Gmail address is testing@gmail.com, and you want to automatically label all work e-mails. Add a plus sign and a phrase to make it testing+work@gmail.com and set up a filter, and labeled it as “work”. To access your filters go to Settings->Filters and create a filter for messages addressed to testing+work@gmail.com. Then add the label work., that’s it. You can add as many filters and label accordingly, as you want.

Lifehacker

Generate unlimited email addresses with Gmail