Security experts at Symantec are warning that spammers are building their own URL shortening services



From v3.co.uk:

Symantec explained that, rather than include the shortened links created on these fake URL shortening sites, spammers build shortened URLs created on legitimate shortening sites like bitly which, if clicked, lead to a shortened URL on the spammer's fake URL-shortening web site.

This in turn will redirect to the spammer's web site, according to Symantec.

  Scammers build fake URL shortening services to improve spam success