What causes Outlook add-ins to not load on startup

[David Phillips]

Pretty basic question - what causes Outlook add-ins to not load on startup?  We all know there are registry hacks to fix these issues, but I'd like to understand the root cause of the issues.  Is it because Outlook is taking to long to load (maybe the user is connecting to too many calendars on open)?  Is it because something on the PC is causing Outlook to load slowly, which in turn is causing it to not load certain plugins? 

In our organization, we have users who randomly have this issue, and it would be great to understand why it's happening.  Adding the reg hack to force the plugin to load is a great workaround, but if Outlook is dumping that plugin to preserve a good user experience, the hack is only adding to whatever is causing Outlook to dump the plugin in the first place.

[#2]

@David Phillips  Yes, it is often because they load slow and this can be caused by something on the computer. The first addin that uses net framework loads it, which can result in it being blamed for being slow. An addin that uses folders in imap or online exchange folders can trigger slow loading too, as Outlook will be slower to load those folders. 

There should be notification in File > Manage COM Addins that says why they were disabled - it should either be due to a crash or because it started slowly. 

[#3]

@David Phillips 

Update Workplace Desktop

Enable your outlook add-in.

Verify the Add-In is Enabled.

Check Slow and Disabled COM Add-Ins

1. Open Outlook.
2. Go to File > Info to display the Account Information window.
3. In the Slow and Disabled COM Add-Ins area, click the Manage COM Add-Ins button. This will open a detail popup.

Edit the Registry

1. Click the Windows Start menu.

2. In type regedit in the search box and press the Enter key. The Registry Editor window will open. Navigate to 
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\Outlook\Addins\AutotaskOutlookPlugin.AddIn
   
3. This registry key has an entry named LoadBehavior. If the Data column value for LoadBehavior value is set to 0, the Outlook plugin will not load automatically. To ensure that the plugin loads automatically, you must set the value to 3. To do so, double click LoadBehavior, enter 3 in the Value data field of the resulting popup, and click the OK button.
4. Restart Outlook. The issue should be resolved.

Regards,

Office 365 migration Expert