I can't speak to Salesforce, but of the many eCommerce platforms I've looked at, none of them return which email link was clicked in their purchase history data -- much less even track that information. Since the original posting date of this idea, Maropost Marketing Cloud has implemented "Last Touch Attribution" for tracking campaign conversions. The attribution settings include the ability to specify the attribution event -- be it email open, link click, or both (with a pre-defined order of precedence.) Read more here in the Galaxy Knowledge Base
