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.

Hiver - Manage Customer Support, Sales and Projects right from your Gmail inbox. Collaborate with Shared Labels, Shared Contacts, email notes, email reminders and email templates

Gmvault - Backup the emails in your Gmail account.

Clean Email - Clean Email is an online service that empowers you to take control of your mailbox.

imapsync - Console-based utility for migrating IMAP mailboxes.

Nylas Mail - The Nylas Cloud API powers your application with email, calendar & contacts features. Built-in features for better email, calendar, and contact management.