Hi Amy Bui,
I do not think this is possible as you describe and here is why:
- The device cannot be known until the email is opened
- Once the email is opened, it's too late to change the URL, uless you run some code
- This would mean running some code in the email client. And sending code in an email is one sure way to have your email classified as malware an never delivered.
- Furthermore, even if your email was delivered, most of email clients would not run the code
- Finally, Marketo does not have any capability to do this at email level
Beyond what Greg notes, if you craft a responsive email so that a tel: link is shown on mobile (and hidden on desktop) and do the reverse for an http: link, you can, in effect, accomplish what you want.
Getting this just right across mail clients will be a chore, though. JS from a redirector page will be an easier build effort.
One thing I don't like from the JS side is that they won't know when they click if it's a call or a pageview coming up. That could be offputting. There also may -- I did some research on this at some point but can't find it right now -- be device-specific restrictions on JS redirects to tel: vs. deliberate clicks on tel:.
I like Sanford's responsive idea, though be aware that media queries work well on Apple i-devices bit only on the most recent versions of Google Android email client. This means that for a large majority of Android devices, this might be very tricky to put to work.
Thank you all! I think it's a lot more effort than it's worth. Hopefully one day Marketo can create something where it is possible. I appreciate all of your responses.
Unlikely that Mkto could ever build in something for this -- it's fragile enough in terms of client support that unless there's a truly universally supported directive (like a literal <link:mobile> tag, supported everywhere) it would be too risky.