Short answers to the questions people search for about mail — opening old files, running out of space, finding the message you need — each with the steps in MailCode and a screenshot of it working. New ones every week.
Apple Mail exports a mailbox as an .mbox folder. MailCode reads those exports, files each mailbox into its local archive as a folder named after it, and makes every message searchable with the rest of your mail — readable without Apple Mail, and without the Mac it came from.
MailCode is a mail client for Mac and Windows that keeps your mail in a searchable archive on your own disk. Free for 14 days.
Mac App Store Download for Windows