I’ve created my HTML signature in an external application and then placed the files (including txt and rtf versions) in the Signatures folder. This signature contains a picture and looks correct when composing a new message or reply. However, when I send the message, the recipient does not see this picture.

I’ve successfully used this signature for years with Outlook 2010 and the issue only occurs when I send a message with this signature from Outlook 2016.

Why is this happening and how can I make my signature work with Outlook 2016?