Andy Boyd

MediaPost’s Melinda Krueger performed some recent tests to determine whether or not you should personalize your email campaign subject. The results were very positive. So positive in fact that every campaign that had a personalized subject achieved a better open rate and often click-though rate.

Before you start personalizing everything you send, she does offer the following: 

"Beware of forcing personalization. Gratuitous personalization can make
you sound like a huckster and detract from your message and your brand.
Even though these results are pretty impressive, this client did not
use personalized subject lines 100 percent of the time."

http://blogs.mediapost.com/email_insider/?p=235