Getting Sender Info From Custom URL
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My app appends a custom URL to email, twitter message, and SMS messages. I want to add a feature where I can identify who the URL came from. 

One way I can do this is by appending a string to the URL on the user's side. But this is costly for Twitter and SMS messages, because it adds characters.

Is there a way that I can obtain the sender info at the receiver side? Can I determine what application sent the URL?

(Thanks for any help with re-tagging this.)