There are advantages to both envelope packages and self mailers. Self mailers usually cost less and require less expensive production (no insertion, matching components, etc.). A self-mailer, however, will not always perform as well as an envelope package. If you are generating traffic or if you have a short easy message (like earn triple points on your XYZ credit card when you use it at gas stations in the next 5 weeks), you may not need a full, classic, envelope mailing to accomplish your objective. If you have a more complicated offer, if you are using segmented copy and personalization or if your audience or your product is more upscale, you will usually see better results from an envelope package.
It is worth a test, though. Some companies find that even though they get lower response from self-mailers, the cost per thousand allows them to generate a lower cost per customer than an envelope mailing. Whatever your test shows remember to continue to test over time. The same format, the same offer, the same package, and/or the same list can atrophy over time. You don’t want your mailings to become so predictable that the consumer assumes they have seen it before...
