My friend and fellow MVP Jim McBee just asked what item types OCS uses for creating items that end up in user mailboxes. There are actually several answers:
- For OCS conversations, you want IPM.Note.Microsoft.Conversation.
- Office Communicator Phone Edition devices use IPM.Note.Microsoft.Conversation.Voice for the call log entries they generate.
- Missed calls notifications are tagged with IPM.Note.Microsoft.Missed.Voice.
These are all easy to set from within Exchange Web Services code; just add a <t:ItemClass> block with the type you want to your CreateItemHeader object.