Overview

 While sending emails via KOFF, the Outlook 2016/2019 is crashing, causing emails staying in the Outbox. The Outlook application will not start or hang, producing the KOFXP.dll and KOFSTR.DLL warnings in the Event logs. The Kerio MAPI DLLs are being blocked by Outlook. Kerio Outlook Connector Offline Edition profile is unable to send emails and may give Security warning loading KOFXP.DLL. This MAPI provider DLL might be harmful to your system on the startup.

Information

Environment

• Microsoft Outlook v2016 & 2019

• Kerio Connect v9.2.9

For end-users using Microsoft Outlook 2019 (1903 - 11425.20228), and the most recent Outlook 2016, the KOFF profile may not work.

Microsoft Outlook 2019 is not fully supported by Kerio Connect version 9.2.9. However, full support for Microsoft Outlook 2019 was introduced in the 9.2.10 release of Kerio Connect.

Root Cause

For unknown reasons, recent Outlook versions do not support entries in the following path:

C:\Program Files\Microsoft Office\root\vfs\ProgramFilesCommonX64\SYSTEM\MSMAPI\1033\mapisvc.inf

Outlook always rejects entries in this path, even if the path to providers in the mapisvc.inf file is updated to point to well-known MAPI providers search paths such as:

• C:\Program Files\Microsoft Office\root\vfs\ProgramFilesCommonX64\SYSTEM\MSMAPI\1033

• C:\Program Files\Common Files\SYSTEM\MSMAPI\

For the moment, there is a valid workaround you can consider, which is to add/modify the following entries in the Windows Registry Editor v5.00: 

• HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\16.0\Outlook\Security\TrustedProviders "KOFXP.DLL"=""

  

• HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Security\TrustedProviders "KOFXP.DLL"=""

  

Refer to the Process section of this article to implement the workaround described above. 

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Process

1. In the Windows "Start" menu, click the magnifying glass icon and type regedit.exe.

2. Select "Run as Administrator" and hit the Enter key to launch Windows Registry Editor v5.00.
   
   
   
   

   If you see a pop-up screen asking whether you allow the Registry Editor to make modifications to your PC, click "Yes".

3. In the Registry Editor, navigate the tree view on the left-hand side to either of the keys below:

   • HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\16.0\Outlook\Security\TrustedProviders

   • HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Security\TrustedProviders

   • If you cannot find the Security or TrustedProviders key in either of the registry locations above, you can create it. For example, to create the first path above:
     1. Select the Outlook key and right-click.
     2. Choose "New" and then "Key".
     3. Name the Security key.
     4. Repeat the process by selecting the Security key and creating the new TrustedProviders key.
        
        
        

        Make sure that you name the new keys correctly.

4. Create the entry in the registry by performing the following steps:

   1. In the TrustedProviders key, right-click and select New and then String Value.
      
      
   
   
   2. Create the following String Value, leaving the "value" field empty:
      
      

      Name: KOFXP.DLL
      Value: 

      The Value for the KOFXP.DLL key should be null. 

   
   

   For more information about the above solution, refer to How to allow MAPI to load unregistered Provider DLLs. The KOFF modified registry entries are attached below.

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   Confirmation

   The error message is no longer displayed in the Event Viewer, and you can now send emails in Outlook versions 2016 and 2019. 

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