ActiveDEMAND makes it easy to move data from other Email Marketing systems into ActiveDEMAND via URL parameters. The parameters AD supports and tracks are
|URL Parameter Label||Recognized Value|
|ad_email||contact's Email Address|
|ad_fname||contact's First Name|
|ad_lname||contact's Last Name|
Thus if you are using an email system that has something similar to ActiveDEMAND's dynamic fields (merge fields in other platforms), you can use the fields to pass information to ActiveDEMAND. For example, if you were sending a prospect to a blog post on your website (that is tracked by ActiveDEMAND) and you wanted to send an email from some other platform, you could append data to the link to let ActiveDEMAND know 'who' clicked the link.
http://www.mysite.com/?ad_email=%CONTACT.EMAIL_ADDRESS%&ad_fname=%CONTACT.FIRST_NAME%&ad_lname=% ... etc.
When AD sees a visitor hitting a web page with the URL parameters filled in, AD will associate the visit to the person identified in the URL parameters ... or will create a new contact if the contact does not exist.