I’ve written before that it’s wise to use an optional survey to find out why people unsubscribe from your emails so you can make improvements. For example, this practice might show that a significant portion of former subscribers say your emails come too often. Based on this data you might logically consider performing frequency testing.
But in the not-so-distant future it’s going to be important that such surveys be as unobtrusive as possible. As Kevin Senne pointed out in a recent post, the FTC has approved four new rule provisions to the CAN-SPAM act.


