- You are using Microsoft Outlook 2010.
- You are using Microsoft Outlook 2013 Service Pack 1 (SP1) or a later version.
- You are connected to a Microsoft Exchange Server 2013 Service Pack 1 (SP1) or Microsoft Exchange Server 2016 mailbox.
- The Exchange mailbox and Client Access (CAS) servers that you are connecting to all have Exchange Server 2013 SP1 or a later version installed or Microsoft Exchange Server 2016.
- The necessary server settings to establish MapiHttp connections are correctly configured.
Note MAPI/HTTP connections are designated in the Protocol column using the string HTTP.
Additionally, if MAPI/HTTP is disabled, Office 365 users receive a Basic Authentication prompt instead of a Modern Authentication prompt.
- Exit Outlook.
- Open Registry Editor. To do this, use one of the following procedures, as appropriate for your version of Windows.
- Windows 10, Windows 8.1 and Windows 8: Press Windows Key + R to open a Run dialog box. Type regedit.exe and then press OK.
- Windows 7: Click Start, type regedit.exe in the search box, and then press Enter.
- Locate and select the following key in the registry.
- Right-click MapiHttpDisabled and then click Modify.
- Change the Value data to 0 and then click OK.
- Close Registry Editor.
- Start Outlook.