Installed add-in not visible in Microsoft Outlook

Problem:

An Outlook add-in (e.g. one of the add-ins installed as part of a CodeTwo product) is not visible in Microsoft Outlook after installation.

Solution:

To solve this problem, you need to delete the extend.dat file from the user's profile and check if the add-in is not listed among the disabled items.

Deleting the extend.dat file

If you are using Microsoft Outlook 2010 or 2013, skip this part and go to section Check the Disabled Items.

To remove extend.dat, follow these steps:

  1. Close Outlook.
  2. In Windows Explorer, choose the Tools > Folder Options, go to the View tab and select Show hidden files and folders.
  3. Go to the folder:

    C:\Document and Settings\<user>\Local settings\Application data\Microsoft\Outlook

    where <user> is the name of the user account for which the problem occurs.

  4. Find the file extend.dat in this folder, and delete it.
  5. Restart Outlook.

Checking the disabled items

To check whether an add-in is listed in the disabled items in Outlook, you need to:

Microsoft Outlook 2003 users:

  1. From the top menu choose Help > About Microsoft Office Outlook.
  2. Click Disabled Items.
  3. If the add-in is included on the list, select it and click Enable.
  4. Restart Outlook.

Microsoft Outlook 2007 users:

  1. Choose Tools > Trust Center from the top menu and click the Add-ins tab.
  2. From the Manage drop-down menu, choose Disabled Items and click Go.
  3. If the add-in is included on the list, select it and click Enable.
  4. Restart Outlook.

Microsoft Outlook 2010, 2013, 2016 users:

  1. Choose File, Options from the top menu and go to the Add-Ins tab.
  2. From the Manage drop-down menu, choose Disabled Items and click Go.
  3. If the add-in is included on the list, select it and click Enable.
  4. Restart Outlook.