Mailstrom, which is a free web-based service, makes it easy to sort, categorize and deal with your mail. It works with Gmail, and other IMAP 3 mail services (but not with all corporate email services). You give it your mail service’s username and password and it imports only the subject line and metadata. It then presents you with the ability to sort that mail by sender, subject, lists you’re on, time sent and social messages and shopping. Sorting by size allows you to find those messages with really large attachments that may be causing you to run low on free storage space on some services. Once you locate all messages that fit in a category, you can select all of them to archive, delete, or move into a different folder. I tested it with Gmail and, though it took a few minutes for Gmail to process all the Mailstrom requests, the mail was either deleted in Gmail per my Mailstrom settings.