2007 VSTO Addin, C#.

We have code that inserts a clickable image (png) signature logo on outgoing
emails.

When it is read by a non-HTML email client it doesn't display the image but
does display the clickable-link URL.

We'd rather this not happen since we already display the URL in a sentence
which we code as white text just below the image so that the plain text
readers will see it but the HTML ones won't.

Anyone know of a way we can suppress the link URL from displaying in
plain-text readers? I'm guessing it depends on the way the particular email
client converts HTML to plain text. I was wondering if there was a possible
universal way to 'trick' most email client software.

If it was normal .net we could have a multi-part email but Outlook doesn't
have this functionality.