At MailChimp, we manage over 65,000 subscriber lists, with over 75 million recipients in them. We’ve seen a sloppy list or two, and have dealt with a delivery problem or two. So we’ve learned a thing or two about how sloppy lists happen, and how to prevent them. Most sloppy lists come from ignorance, not evil. But that doesn’t make it any less stupid. So here are some stupid list management mistakes to avoid:

• Don’t send to a really old list. If you do, ISPs will say, “Siiiigh. Looks like this sucker bought an old email list from a spammer, and is trying to contact a bunch of email addresses that have expired, or never existed in the first place. So let’s block him.” People ditch or change or lose their email addresses after about a year (see this post on address-abandonment from Word To The Wise.). If you haven’t been sending regular email campaigns to your customer list, you’ll need to clean that list out before you begin emailing them any serious campaigns. Note that “clean your list before sending” does not mean, “blast an email, and see who bounces.” Remove emails that are too old, remove “role” email addresses (webmaster@, sales@, info@, etc), and remove anyone that did not specifically request email marketing from you. We’ve heard that there are companies who can clean your list for you, but we’ve never used them ourselves.
• Never, ever, ever purchase an email list. If you want to grow your list, partner with a company that has the same audience that you target, and have them send an email on your behalf in order to get those people to subscribe to your list. Here’s an excellent example of how to do that, and here’s an article with mistakes to avoid.
• Use the confirmed opt-in method on your email signup forms. This method sends a confirmation email that the subscriber has to click in order to complete the subscriber process. If you just use the “single opt-in” method, your list is vulnerable to prank submissions, typos, and spambots that plug in spam trap addresses.
• Never scrape lists from websites, or assume that you can just add “sales@” or “info@” onto the front of a company’s domain name in order to reach its “decision maker.” Yes, I’ve had to shut down accounts for doing such idiotic things with their lists. It only takes one or two spam complaints from these “role addresses” to get yourself blocked. Some websites actually are setup to track email scraping.
• Educate your sales team on email marketing laws and best practices. Tell them they can’t just export a giant email list from your CRM of “prospects I’ve met over the last 10 years at various tradeshows” and “blast an email to ‘em.” It’s possible your sales people don’t care one bit about email etiquette. They just want to make their commissions (which is the way it should be) but there are laws that can land them in jail, or get them fined by the FTC. And jail time and fines can really eat into their commissions. If that doesn’t work, you’ll need to learn how sales people talk. Hint: try some profanity (and here’s a slightly-safer-for-work version).
• If you’re an agency that’s helping a client send email marketing for the first time, here’s a guide on how to tell if your client might be a spammer.
• Don’t just email all the contacts in your Outlook Address Book. There are email addresses in your address book that you probably don’t know are in there, like: tech support contacts from companies you’ve requested help from (techies get really mad when they receive emails from people they don’t recognize, and they know how to report you for it, fast), and companies who’ve sent you email order receipts; friends and family (who may enjoy personal emails from you, but not necessarily your company)
• Tradeshow lists can be dangerous. Here are some tips for dealing with tradeshow email lists.