We use Google apps for a number of our office applications & Gmail handles our email. Recently I’ve been noticing that the storage in our Google account has been getting pretty full.
Fortunately, a quick search is all it takes to identify messages worth deleting. I used the search operators older_than:1y size:500KB to filter messages that were over a year old & larger than 1/2 MB.
To get rid of them all, tick the select all box (top left) & then click the Delete button. Be careful to deselect any emails that you want to keep. Repeat the process if you have pages of emails to delete.