ISSUE:

• Signature is not showing when creating a new email or sending a reply
• Signature is only applied after email is sent
• The add-in works in Outlook on the web but doesn't appear in the classic Outlook for Windows.
• The add-in doesn't automatically add signatures to emails.

RESOLUTION:

How to clear cache in Outlook for troubleshooting purposes

• Open the classic Outlook for Windows and go to File > Options > Advanced.
• Check if the Show Apps in Outlook option is enabled (see Fig. 1.).
  
  
  
• If enabled: go to %userprofile%\AppData\Local\Microsoft\Outlook\HubAppFileCache and delete all contents of this folder.
• If disabled: go to %localappdata%\Microsoft\Office\16.0\Wef and delete all contents of this folder.
  
  
• Restart Outlook.
  
  
• You can now verify if the CodeTwo Outlook add-in works as expected