Click the cogwheel in the bottom-left corner, and then click Settings.
From here, click the Filters tab.
Then, click Add Filter and follow through the steps. The first step asks what types of emails (criteria) you would like the filter to effect. *For example, if you’d like the filter to effect every message you receive, you can select “To or Cc contains user@emailaddress.com”
Click Next and add the actions you would like to be applied to your criteria. You can tick Run this filter on messages already in to retroactively apply the filter. If this is unchecked, your filter will only affect future messages.
Click Finish.
That’s it! The webmail filters interface can automatically manage your emails in the background. This functionality works great even when you’re signed in to IMAP on multiple devices.