I found the answer and am posting it here for anybody who has the same issue.
My system is Windows 10 and I have been trying to get rid of Outlook simply because it is just plain awful. I have tried a few different email clients but could never get one of my programs (which happens to be 16 bit) open up the eM Client… it would always open up Outlook.
Here is the solution:
When you change the Windows default email client, it makes a change to the following registry key:
HKEY_LOCAL_MACHINE\Software\Clients\Mail::(default) registry value
where it names the default client
BUT it doesn’t change this key:
HKEY_LOCAL_MACHINE\Software\WOW6432Node\Clients\Mail::(default) registry value
When I manually change it, then my 16 bit program then connects to my default email Client.
Mike