Do not use URL shorteners in your email
September 25th, 2012
Spamhaus has listed bit.ly on the Domain Blocklist (DBL) for allowing spammers to abuse their redirector service.
Thus, if you use a bit.ly URL in your email, that message is much more likely to be labeled as "spam" by recipient filters. In fact, you should avoid using ANY URL shorteners in email, since these blocks come and go as the services get abused by spammers.
Here is a good article about using URL shorteners.