What are some alternatives?
When comparing iSync and IMAPSize, you can also consider the following products
OfflineIMAP - OfflineImap synchronizes email between an IMAP server and a MailDir or between two IMAP servers.
MigrationWiz - MigrationWiz provides on-demand mailbox migration services through a fully automated cloud-based...
imapsync - Console-based utility for migrating IMAP mailboxes.
Yippie Move - The world's best email transfer tool
MailStore - MailStore Home - A 100% free single-private-user desktop solution
mnIMAPSync - mnIMAPSync - Java IMAP email syncing tool