Great Subject Lines!

[JesseJ]

I wouldn't want to take up the valuable real estate in the subject by repeating the phone number each time. If all of your subject lines say the same thing, how do you generate interest for a new message? Have you tried split testing to see how the open rates compare?

Here's an article that Return Path posted yesterday on subject lines:
Subject Lines Are More Important Than Ever: 4 Ways to Optimize | The Return Path Blog

There has been absolutely no increase in open or read rate. The claim they make is that a phone number helps dodge spam filters. I have no idea how accurate that is but it sounds questionable. I've dropped the phone numbers from my subject lines for awhile now.