This post looks into an issue, where public folders, Offline Address books, and Free/Busy information are not replicating to the new SBS 2008 server after following steps from “Move Exchange Server public folders for Windows SBS 2008 migration”. The key thing to remember is that public folder replication messages use SMTP for transport, therefore if you have modified settings to the default SMTP Virtual Server these messages may never reach the destination. The SBS 2003 BPA will detect some of these mis-configurations, so make sure to also run both the Exchange BPA and SBS BPA.

Full Article: SBS Blog