Of course, getting someone to open a paper envelope is a heck of a lot easier than getting past the subject line. Because with a paper envelope you have plenty of space to write teaser copy and add photography or illustration if it's appropriate. You can create something unique that stands out from all the other mail in the pile and screams out benefits that will get the prospect to read the letter within. Subject lines all look the same and have to be kept short. This means that every subject line must communicate extremely quickly.
Subject lines are well worth testing.
I asked him about his take on subject lines. Five thousand names is the minimum you need for an e-mail test cell. It's worth doing some testing because a strong subject line can double the response. It will be viewed as spam and won't be opened. I personally believe that this is just another suburban legend and that you really don't have to sweat it.