We received this email from our friends at KnowBe4.com today:

CryptoLocker is back big time. Researchers have spotted a sudden resurgence this year, specifically identifying clusters of attacks in Europe and the U.S.

For people new to the ransomware racket, Russian cybercrime gangs tend to test and debug their campaigns in Europe, and then attack America in full force. CryptoLocker is ransomware's still very potent granddaddy, and pioneered this highly successful criminal business model in September 2013, hundreds of copycats followed

As always be vigilant with your email, if you didn't expect it don't open it and DO NOT click on embedded links to sites from these suspicious emails. For more on this specific issues read here.