[SalesForce] Can AMPScript parse JSON

You'd likely not use AMPScript for this as SSJS handles JSON natively. You could try putting SSJS into your email, but you'd be on your own with respect to Tech Support with any issues you encounter with sending these emails. They don't have much of a sense of humour when it comes to SSJS in emails - the performance is poor and the back-end logging tech support has access to is pretty non-existent.

My advice would be to use a Landing Page to do the transformation from JSON to HTML using SSJS and include this in your email by doing a HTTPGet() to the Landing Page. If it's the same content for more or less everyone, make sure you use the TreatAsContentArea() AMPScript function around the HTTPGet() or use a before;httpget command in the content area in the email to cache the content and avoid making many wasteful calls to this page to get the same content.

This example I put together a few years ago isn't exactly syndication, but the final section on the "Sample Contact Page" shows making a HTTPGet() with SSJS and interrogating the JSON response, which is pretty much what you need to do...

Retrieving Information From a Third Party API Using a Landing Page

So I may have not asked the correct question for what I was trying to accomplish. This worked for me. Passing Recipient_List as a JSON string attribute.

"[{\"name\":\"john doe\",\"email\":\"john.doe@mail.com\"},{\"name\":\"jane doe\",\"email\":\"jane.doe@mail.com\"}]"

With the JSON string input shown above.

%%[
   var @json
   set @json = AttributeValue("Recipient_List")
]%%

{{.dataobject JsonVar type=variable source=@json maxrows=20}}
   {{.data}}
        {"target":"@Json"}
   {{/data}}
{{/dataobject}}
{{#each JsonVar}}
   <p>{{name}}, {{email}}</p>
{{/each}}