Currently when Marketo wraps Skype URI links, the redirect causes a 404 error as the tracking server does not understand how to handle the URI. The current workaround is to use the mktoNoTrack class on the link to prevent tracking, but then that removes a potentially useful data point for marketers.
Example of Skype URI:
<a href="Skype:JesseJames?chat">Chat with Jesse</a>
Error and URL Sample (domain redacted):
http://info.<customersite>.com/n/uHB000QU46000R04hmHBF10
404 Not Found
The redirect url is empty