Why does this happen?
Microsoft has some security measures in place to prevent slow add-ins from running inside Outlook. However, in many cases, add-ins without fault are being mistakenly marked as slow and disabled by Outlook. If this is not immediately corrected, Outlook may permanently disable them with no way to re-enable them via the user interface.
What can I do about it?
Please run through the following steps to fix this issue:
Be an Administrator
Make sure you run Outlook as an Administrator when you enable the add-in (Right click - Run as Administrator)
Force Outlook to always enable the add-in
By default, the Mailock Add-In installs with parameters that force Outlook to ‘Always enable this add-in’.
You can check this setting and reset it if necessary.
On the File tab, click "Manage COM Add-ins" under "Slow and Disabled COM Add-ins".
You'll see a list of add-ins. Locate the Beyond Encryption entry and click Always enable this add-in.
Changing the Load Behavior
If the Add-In setting above is correct and the Mailock Add-In is still not loading when Outlook is opened, then it may be due to the registry setting that controls how the Mailock Add-In is loaded. The following steps detail the process you should follow to correct this registry setting.
On the Outlook File tab click Options, Add-Ins and with the ‘Manage:’ selection set to ‘COM Add-Ins at the bottom of the page, click the ‘Go…’ button and select the Beyond Encryption Add-In from the resulting list.
You will be able to see the current load behavior of the Mailock Add-In which should be set to "Load at Startup" like this:
If load behavior is set to any state other than ‘Load at Startup, follow these steps:
If the LoadBehavior key is anything other than "3" then follow these steps:
If you would like further information on LoadBehavior and the values that it can be set to, the following MSDN article covers this: https://msdn.microsoft.com/en-us/library/bb386106.aspx#LoadBehavior