There’s still a lot of education to be done on the topic of buying lists, why it’s a bad idea, and why it should be avoided.

Setting aside the emotional and ethical question of whether it’s right or wrong to buy lists, there are some very practical reasons that bought lists will damage your ability to deliver mail successfully. Here are the top three.

1. Purchased lists are filled with bounces and invalid addresses. If you don’t mail a list for a long time, then you mail it, it has a very high bounce percentage. High bounce percentages are one of the measures ISPs use to determine who’s doing something bad and should be blocked. If a lot of your attempted mail bounces, you look like a spammer.

Whoever you’re buying the list from will claim everything is cool and great and assure you it’s all opt-in. That might have been true at one time (but probably wasn’t). Ultimately, though, they’re looking to sell you as much list data as possible. They’re probably not mailing the list themselves, just selling it to a lot of different people. If they’re not mailing, they’re not processing and removing addresses who bounce. You buy the list, you buy it, and boom, you have huge bounces and delivery problems.

2. Don’t forget spam traps. Spam traps are email addresses that feed straight into spam filters. Hit just a few (or often just one) of these, and your mail goes to the spam folder or gets blocked. ISPs take addresses that should never be on their lists (usually common typos and forgeries) and long dead addresses (things that have been bouncing and would not have on your list if you handled bounces properly) and turn them into spam traps.

Even if the person you buy the list from was mailing it first, there could be (and probably still are) spam trap addresses on those lists. The only way to remove them is to re-engage your list. Dump inactive subscribers. Ask everyone on the list to click on a link to re opt-in. See, spam trap addresses accept the mail just fine; they don’t return a bounce. But they don’t open and click. So you don’t know which addresses are spam trap addresses. And whoever you’re buying that list from probably is not re-engaging their list – because it could dump 90% or more of the addresses on that list as being invalid or uninterested. That reduces the amount of data they’re able to sell you, which is likely at odds with the list seller’s financial motivation.

3. And finally, consider recipient dilution. What is recipient dilution? That’s where you and 900 other senders mail the same list. There have been a few cases, with clients we’ve terminated, where I test somebody’s signup process, and find that after about a day, they get a hundred emails from 90 different senders. A hundred emails!

Think of how overwhelming that would be in your inbox. Do you want a hundred emails all at once? Regular users are going to be overwhelmed and report all those messages as spam. Your message is not going to stand out, as everybody that list probably has a very low tolerance for messages they don’t recognize. You’ll be just another one of the big pile of unfriendly spammers pounding the heck out of their email account.

Or, let’s assume a different scenario. Perhaps the list owner is compiling the list over time, and will end up sending it to different people at different times. The recipients on this list are going to keep getting mail they don’t recognize that people they don’t know –forever! The list will be sold and sold and sold and sold, and if you buy it, and send to it, you’re just one of the people making the people on that list miserable.

Can you imagine ending up on one of these lists? Even if you meant to sign up for a list that is going to be sold 500 times – after a short while you are going to start getting very upset. You’re getting more and more mail from people you don’t recognize and you didn’t expect that mail and a lot of it is mail you didn’t want. And it keeps coming and coming and coming. You know what I call that? Spam.

ISP users will report that mail as spam. ISPs will listen to those reports, and you’ll be branded a spammer (and rightly so). You’ve got no hope of making it to the inbox when that happens.

My team and I have great relationships with ISPs. But no ISP will ever knowingly want to help a sender doing things this way. If you want to get to the inbox, or not get booted out of the inbox (often permanently), then you need to avoid these practices at all costs.

There are lots of legitimate ways you can build your list. But buying a list isn’t one of them.