The GroupWise 6.5 Internet Agent is fully functional only when running against GroupWise 6.x domains and post offices. If you run it against a GroupWise 5.x domain or post office, users on GroupWise 5.x post offices can send and receive Internet messages (SMTP support), but cannot use POP3 and IMAP4 clients to access their mailboxes.
The GroupWise 5.x/6 Internet Agent can run against a GroupWise 6.5 domain and post office, which means that you can continue to use it until all domains and post offices are updated to version 6.5.
For a list of new features in GroupWise 6.5 Internet Agent, see What's New in GroupWise 6.5.