From: Yahoo! [email@example.com]
Date: 14 June 2013 08:42
Subject: We want you back
Signed by: email.yahoo-inc.com
We want you back.
Sign in now
Keep your account active by signing in before July 15th, 2013.
By reactivating your Yahoo! account you can experience the new Yahoo! Mail, more personalized content on Yahoo.com, and so much more.
Once your account is reactivated, every time you sign in, your account will be extended by 12 months.
Need to reset your password?
Assistance is here!
Have additional questions?
Visit Customer Care
Yahoo! Customer Experience
It just looks so much like a phishing email that a sensible person probably wouldn't click on it.. except, the links in the email actually go to Yahoo! and the email has been signed, so this really does appear to be a genuine email.
Except for one thing.. the email address that it was sent to has never been used to register a Yahoo! account. Yup.. something somewhere is not right with this email..
Yahoo!'s explanation can be found here.