Pay attention! This solution only works for Outlook 2013 and Outlook 2016

In some cases, Outlook may no longer load the add-in automatically at startup, or it will crash immediately after you activate the plug-in. There can be several causes for this problem. The most common is that Outlook disables the add-in because the add-in in the past has done a bit longer about loading than Outlook can handle. The add-in also gets the load behavior status "deleted".

List of add-ins

To view the list of the enabled and disabled add-ins, go to Outlook:

File> Options> Add-ins

In the add-ins dialog, click on start at the bottom of the screen when managing. The following dialog will appear:

Solution

To force Outlook to always load the add-in at startup, you must implement the attached registry adjustments.

• Download and open the file ResetAttachingIT.zip (at the bottom of the page).
• This contains a file called Outlook2016-rest-AttachingIT.reg and Outlook2013-reset-AttachingIT.reg.
• If you run this and restart Outlook, the add-in should be permanently loaded again. You may not have permission to modify the registry. Send this article to your IT supplier so that they can do this for you.

For the advanced user, here the plaintext version of the registry adjustments:

Outlook 2016:

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\16.0\Outlook\Resiliency\AddinList] "zzzzzzz.AttachingIT"=dword:00000001
[HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\Outlook\Addins\zzzzzzz.AttachingIT]
"LoadBehavior"=dword:00000003
[-HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\Resiliency\DisabledItems] [HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\Resiliency\DisabledItems]
[-HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\Resiliency\CrashingAddinList] [HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\Resiliency\CrashingAddinList] [HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\Resiliency\DoNotDisableAddinList] "zzzzzzz.AttachingIT"=dword:00000001

Outlook 2013: 

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\15.0\Outlook\Resiliency\AddinList] "zzzzzzz.AttachingIT"=dword:00000001
[HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\Outlook\Addins\zzzzzzz.AttachingIT]
"LoadBehavior"=dword:00000003
[-HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\15.0\Outlook\Resiliency\DisabledItems] [HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\15.0\Outlook\Resiliency\DisabledItems]
[-HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\15.0\Outlook\Resiliency\CrashingAddinList] [HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\15.0\Outlook\Resiliency\CrashingAddinList] [HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\15.0\Outlook\Resiliency\DoNotDisableAddinList] "zzzzzzz.AttachingIT"=dword:00000001