[btilly]

Depends where the copy is. Changing a couple of words in an email subject line can and often does make a huge difference. Of course the fine line you walk is that some of the most effective words at driving behavior (Free! Now!) are also effective at getting you marked as spam.

[m4xt3r]

I think wording in the subject line is important, because it is the only thing a user sees. There are no other factors that affect whether he will open it or not.