Twitter is routing links within Direct Messages through our link service to detect, intercept, and prevent the spread of malware, phishing, and other dangers. Any link shared in a Direct Message has been wrapped with a twt.tl URL.
Twitter is scanning all shortened URLs befor being posted
Links reported to us as malicious are blacklisted, and we present users with a page that warns them of potentially malicious content if they click blacklisted links. Twitter wants users to have this benefit on all tweets.
Raffi Krikorian, a technical lead on the Twitter Platform Team, explained in a Google Groups posting that the t.co system will always format links to 20 characters.
Additionally, as we mentioned at our Chirp developer conference in April, if you want to share a link through Twitter, there currently isn’t a way to automatically shorten it and we want to fix this. It should be easy for people to share shortened links from the Tweet box on Twitter.com.
To meet both of these goals, we’re taking small steps to expand the link service currently available in Direct Messages to links shared through all Tweets. We’re testing this link service now with a few Twitter employee accounts.
This change will is specially made for mobile users. In addition to a better user experience and increased safety, routing links through this service will eventually contribute to the metrics behind our Promoted Tweets platform and provide an important quality signal for our Resonance algorithm—the way we determine if a Tweet is relevant and interesting to users. We are also looking to provide services that make use of this data, an example would be analytics within our eventual commercial accounts service.
Informative blog post, thanks for keeping me busy! Twitter RULES!