Lotame - Make your data actionable, learn about your most valuable customers, improve ROI by targeting the right audience and increase relevance across screens.
imapsync - Console-based utility for migrating IMAP mailboxes.
V12 Data - V12 Data offers rich data sets with verified addresses and emails for personalized marketing campaigns.
MailStore - MailStore Home - A 100% free single-private-user desktop solution
Google Audience Center - 3 votes and 6 comments so far on Reddit
audriga Email and Groupware migration - Easily migrate your email, contacts, calendar items and tasks to your new provider or server. No software installation is required.