Setting a Default Profile
Applies to: Outlook 2013 | Outlook 2016
The default profile is the profile that is used if you do not explicitly specify one in the call to MAPILogonEx, setting instead the MAPI_USE_DEFAULT flag.
To establish a default profile
Call the MAPIAdminProfiles function to retrieve an IProfAdmin interface pointer.
Call IProfAdmin::SetDefaultProfile. SetDefaultProfile sets the PR_DEFAULT_PROFILE (PidTagDefaultProfile) property for the new default profile and removes the setting for the previous default profile.