That’s what I was afraid of, it’s a platform bug specifically with the unrecognized URL scheme.
Try it with the whole <a> tag (including <a> through closing </a>) in a Text {{my.token}}, still including the class="mktNoTrack". If that doesn’t work, put it in a Velocity {{my.token}}. Let me know the results.
EDIT: there’s no such bug, the user is testing in the wrong environment. Not all devices support the sms: scheme is all.
@talhakhalid see my edit above. I actually don’t see any problem w/Marketo rendering such links in the email at all.
Your F12 Inspector isn’t the way to tell if something exists in the raw message Marketo sent, because the mail client is stripping out HTML tags it doesn’t support. You have to use Show Original Message, Show HTML Source, or similar to show the actual message, in which case you’ll see the <a href="sms:...> is indeed output correctly.
However, not all devices and mail clients support the scheme. For example, my Outlook for Android doesn‘t; my webmail, viewed on Chrome Mobile on the same device, does.
