Disk Drill by Cleverfiles - Recover any type of deleted files in Windows & Mac including Office documents, messages, and media files quickly and easily.
imapsync - Console-based utility for migrating IMAP mailboxes.
MiniTool Power Data Recovery - MiniTool Power Data Recovery is a freemium data recovery tool that works quite well considering the basic version is the only free aspect of the app.
Gmvault - Backup the emails in your Gmail account.
Wondershare Data Recovery - Recoverit data recovery software enables you to recover all data types in any data loss scenarios easy,fast,powerful for Windows computer with 96% high recovery rate.
Cryoserver - Cryoserver is an all-in-one email archiving solution that empowers you to preserve your email in a tamper-evident archive, making you transform your data into a useful archive for everyday use.