How do they help achieve Inbox Zero?
Unibox has the most unusual approach here: while traditional labels and folders are still available, its core interface is based on classifying messages by sender. It’s something you understand instantly: it’s like a prettier Messages, and it’s really easy to find files you’ve previously sent or received.
Thunderbird, Outlook, Postbox and Airmail use rule-based filtering to classify mail, and it’s easy to set up complex IF/THEN criteria in order to automatically move, delete, archive or categorise emails.
Mailbox, though, is much simpler: when an email is in your inbox, it wants you to triage immediately with a swipe across the message. Swipe right to archive it, or swipe left to either flag it for action later or to add it to a list. All three options remove the message from your inbox, with the latter two popping the email up again at the specified time and filing it, respectively. It’s something that works very well on iOS but feels a little simplistic on a Mac, but if you’re an Inbox Zero obsessive you’ll like it a lot.
When an email arrives in your inbox, Mailbox wants you to swipe it immediately.