What are some alternatives?
When comparing iSync and OfflineIMAP, you can also consider the following products
imapsync - Console-based utility for migrating IMAP mailboxes.
MigrationWiz - MigrationWiz provides on-demand mailbox migration services through a fully automated cloud-based...
MailStore - MailStore Home - A 100% free single-private-user desktop solution
Yippie Move - The world's best email transfer tool
mnIMAPSync - mnIMAPSync - Java IMAP email syncing tool
IMAP Upload - IMAP Upload is a tool for uploading a local mbox file to IMAP4 server.