If you are not familiar with the Email Insider Summit, it's pretty much as its name describes. A group of 100 or so of the top email folks in the country get together to share ideas, network and have some fun. Attendees include marketers from big companies, executives from vendors and the occasional media person. This is the second Email Insider Summit, and the folks at MediaPost are already planning another two for 2007.

I will be posting several entries over the next several days from the notes I took, but let me start by telling you about the number 49.

A recent study by ReturnPath presented by Stephanie Miller, vice president of strategic services, found that the maximum number of characters in a subject field should be 49. She said that lines consisting of 49 characters (presumably give or take a few) performed 75-percent better than longer subject lines and much shorter subject lines. Stephanie, who also organized the summit, pointed out that your actual numbers may vary a lot, and that testing is always called for when determining what works best for each marketer.