Let’s be clear right up front: all mailing lists are dirty. Some are just dirtier than others.

By dirty, I mean bad names, bad addresses – non-deliverable mail.

When you rent a mailing list, most list owners will only guarantee 92-95% deliverability. Put another way, you may see 5-8% non-deliverable mail – which, if you haven’t seen it, can stack up pretty high if they are coming back to your office.

Why so high? On average, 15-20% of the population moves every year. That’s about 1.5% per month. On the business side, you have frequent movers as well – but you also have people changing jobs and businesses that have closed or gone bankrupt. So even the most aggressive list “updater” will always have a significant number of non-deliverables.

Most of us never see our non-deliverable mail. Unless we mail first class or add “Address Service Requested” to the address box of our mailer, non-deliverable mail gets thrown out. “Address Service Requested” is a service the post office provides that alerts you to non-deliverable and will provide a forwarding address if known.

If you are mailing to your house list and you want to keep it up to date, we always recommend using “Address Service Requested.” You will pay the post office a small fee for each address that gets updated – a small investment to your keep your own list relatively clean.

But if you are renting a list for one-time usage, what are you going to do with the updated address? You can’t mail to that name again without paying for it. Let the list company worry about non-deliverables.

You need to worry about the performance of that list.

Now you might think that deliverability is an indicator of list performance. On the surface, that seems logical. If a list has a high non-deliverable rate, it should produce a lower response. Right?

Not necessarily.

Several years ago, one of our clients tested 10 different lists and list segments. One list from a small, highly targeted industry newsletter produced a very high non-deliverable rate (presumably because the list owner was less aggressive about keeping it up to date), but the same list also produced the highest response rate (presumably because it matched our customer profile more precisely).

For list performance, look at the response numbers (response rates, cost per response, etc.) and don’t get side-tracked by the much less meaningful non-deliverable rate.

This is not unlike the great athlete who never shows up on time. Yes, it’s aggravating, bad for morale and all that – but if you’re getting the performance, you might need to overlook the tardiness.




Written by Bob McCarthy

This article may be reprinted without permission as long as the article includes the following credit: Bob McCarthy is a freelance copywriter and consultant specializing in direct marketing and lead generation. His website is He can be reached at 508-473-8643 or by email at

About Bob McCarthy

Bob McCarthy is a direct response consultant and copywriter with a focus on direct mail, email and digital marketing. Bob works with B2B, B2C and Non-Profit clients. You can download his free ebook, "Making Snail Mail Work: 13 Lessons in Direct Mail Strategy."