Opinion on yellow letters

[Eric Black]

We have been using a yellow letter campaign for the past few months and wanted to get some opinions.

We would like to get your opinion on if the letters should say the exact same thing each time or should each letter be a little different? We are currently using 3 letters that we rotate. We're not getting a very good response rate and would like to improve what we are doing.

We also are wondering if using different colored paper is a good strategy or if you should stick to one color.

Thanks all.

Eric