MAPI over Http issue for OpenOtherMailBoxFromGAL

Hi Guys,

I create 2 profiles for a user which has "receive-as" right for the mailbox database in my lab, one profile "Chunk-RPC" is for Outlook Anywhere, another "Chunk-Http" is for MAPI over Http.

when I logon the "Chunk-RPC" with MAPI, and use the session to Open other user's mailbox from gal, everything is good and no problems, but when I use the "Chunk-Http" to logon, I cannot open other user's mailbox,  just got "MAPI_E_CALL_FAILED==0x80004005" error code from OpenMsgStore function, Could you please tell me what's the key issue?

Thanks,

Mic