Dynamic hidden form field triggers

[Stephen_Usher]

We are trying to take a form, that is used in several places via embed code and have one of the instances it's used trigger an email with a link to a pdf. The link to the pdf is not hosted on Marketo, there is a possiblity the link will change in the future. Would we be able to use a hidden form fields that will a) only send the email when that specific form instance is filled out and b) automatically update the link in the email if it is updated later? 
 

[SanfordWhiteman]

If you are comfortable passing the PDF URL as a hidden field (thus someone inspecting the page code could see it) then just pass it directly to a custom field stored on the lead ("Last Download Requested").

If you want to make it (somewhat) harder for the user to obtain the URL, then have the hidden field contain only a friendly name.  Then set up a {{my.token}} that translates that name into the URL.  You can maintain the {{my.token}} over time and include it in the email template.