How to enable the GetReplied Add-In if Outlook disabled it. 

If the GetReplied Add-In is missing from your Outlook application, it's possible that Outlook disabled it to speed up the starting process. To enable it again, follow these simple steps:

Go to File > Slow and Disabled Add-Ins

A window will prompt with a list of current disabled Add-Ins. Please Click on 'Always Enable this Add-In' under the GetReplied item 

If the GetReplied Add-In is not listed on the current disabled Add-Ins, maybe Outlook put the Add-In on the 'Inactive Application Add-Ins'. In that case:

  •  Go to File > Options (Outlook will open a window with general settings).
  •  Click on the Add-In tab.
  •  Select the 'Go' button.
  •  Search for 'GetReplied' and make sure it's checked, then click 'OK'.