imapsync - Console-based utility for migrating IMAP mailboxes.
Clearbit - Clearbit provides Business Intelligence APIs
OfflineIMAP - OfflineImap synchronizes email between an IMAP server and a MailDir or between two IMAP servers.
ZoomInfo - ZoomInfo is a B2B database providing detailed business information on people and companies.
Fetchmail - The Fetchmail Project
InsideView - InsideView aggregates and curates all the company and contact data, news and social insights, and professional connections you need to do business better.