Emails to mail-enabled public folders arrive as "posts" instead of emails

By default, Exchange stores inbound email to public folders as "posts" (IPM.Post item type). You can change this via a registry setting:

1. Open Registry Editor (regedit) on the Exchange server.
2. Navigate to: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeIS\Public-{GUID} (replace {GUID} with your public folder store GUID).
3. Create a new DWORD value named Incoming defaults to IPM.Note.
4. Set the value to 1 to store as email (IPM.Note); set to 0 to store as post (IPM.Post).
5. Restart the Microsoft Exchange Information Store service.