Shortened URLs used in spam

I use Twitter to keep people updated on my latest and most interesting articles and books, it shortens the URL when I include the link. I always thought it was convenient, especially since it saves space–which is of course at a premium when you’re Twittering. But who else is using those URL shortening services, and towards what end?

I saw a very informative post today on the Unweary blog that points out some risks I had previously not considered when using a third party service to redirect you to a Web page. Normally, when I get an email that contains a link, I will always mouse over the URL so I can see if it’s really going to go where it says it will. If the email claims to be from my bank, but the URL is from some domain in Russia, then I know it’s obviously bogus. But with the shortened URLs, this becomes impossible. You have to just click to see where it goes. Apparently, spammers have discovered this as well, and are using these URL shorteners in their spam emails as another way to disguise a link’s true destination. The shortened URL may also bypass spam filters, which may recognize a spam domain but may let the shortened URL get through.