Email List Hygiene: Keep It Clean

Blog Administrator | Article, Direct Mail, Mailing Lists | , ,
By Spencer Kollas, director of delivery services, StrongMail Systems
Last month, I provided best practices to maximize email deliverability with the first step in this series, data capture. The next logical, and critical step is applying effective list hygiene techniques. Maximizing email deliverability does require managing many factors, but once you understand the various components, the process is fairly straightforward. 
Even if you’ve followed all of my data capture advice, you still need to engage in list hygiene to ensure its quality. Without proper list hygiene, you risk losing contact with your customers, damaging your sender reputation and getting your emails blocked by the ISPs. 
For example, if you continue to send emails to accounts that have been closed for some time (i.e. to “unknown users”), ISPs will take notice, which could lead to getting your email blocked. You also run the risk of getting in trouble with spam traps. Essentially, an unclean list tells the ISPs that you don’t care about your customers, or about following best practices. Maintaining a good reputation also requires that you respond to unsubscribe requests and bounce data immediately.
Reputation aside, list hygiene also makes financial sense. Restoring customer connections and increasing deliverability leads to increased conversions. If you use an ESP, removing bad addresses will also eliminate the associated CPM charges.
As a rule, you should always do an initial list hygiene check before you send from your database or begin working with the ISPs. Even if you don’t have any bounce data, you can still verify if you’re sending to domains that no longer exist, such as and many others. 
Another item you want to look for is to see if your list includes distribution accounts such as or No one person should be signing up for your messages with a distribution email address; not everyone on that list has requested your content.
List hygiene best practices
The following activities are an essential part of a successful list hygiene program:
Scrub your lists regularly.
Scrubbing your list is simply making sure that you are keeping it as clean as possible by running your list against a list of known bad domains and role accounts. While you should remove unsubscribes and relevant bounced email addresses immediately, you should also scrub your lists on a regular basis. The volume and frequency of your mailings will determine how often you want to scrub them. Scrubbing should go beyond removing duplicate addresses. 
Bad domains need to be removed or corrected right away. Closely review your failure reports, identify bad addresses and evaluate whether they are the result of a data capture problem or a nonexistent domain. If you’re experiencing a high rate of failures, you’ll want to determine how those addresses got onto your list and if they’re indicative of a data capture problem. Simple data entry mistakes like misspelled domains (,, et cetera) can be easily corrected. 
Remove distribution accounts.
Mailing to a distribution account is never a good idea. Not only is it an unsuitable address for connecting with a customer (the equivalent of sending a letter to “occupant”), ISPs are looking for such behavior. Plus, it’s also sure to facilitate spam complaints from members of the list. You can easily remove distribution accounts by adding “all,” “sales,” and other common addresses to your suppression list. 
Remove “spam” email addresses.
One simple step that can be easily overlooked is to remove email addresses with the word “spam” in them. These are most likely associated with spamtraps, which can lead to you getting blacklisted by ISPs or antivirus companies. 
Remove inactive addresses.
Review the email activity of your customers and compare open rates with the frequency of the email sent to them. One example might be, if you send a newsletter every two weeks and a customer hasn’t opened one email in the last six months, you should remove the address from your master list. This type of program needs to be something that is specifically built around your company and your mailing practices. You can then add them to another list that is designed to reengage inactive customers with other types of communications.
Use data checkers.
You can avoid a lot of bad addresses by putting some common data checkers at the point of data collection on your website. These checkers can ensure that the entered email address is properly formatted before it is accepted into the database. Identifying the errors at the point of entry gives you the opportunity to have users correct the mistakes as they make them. One common problem that many marketers run into is a customer entering an “!” instead of a “@” as part of the email address.
Feedback loops
Along with keeping your lists clean, you also need to set up all available feedback loops with ISPs and other receivers. Feedback loops will keep you from sending messages to customers who have indicated that they no longer wish to receive your communications. Not only is it a good idea to respect the wishes of your customer, it is also an important practice for maintaining a positive sender reputation. Abiding by feedback loop complaints can demonstrate to ISPs that you are committed to keeping your list as clean as possible and are not interested in spamming their customers.
The importance of list hygiene cannot be overlooked as an essential email marketing practice. By employing the practices mentioned above, you can make great strides in improving your deliverability rates and safeguarding your reputation. Of course, it’s just one aspect of deliverability, so be sure to check back next month for the next installment in this deliverability best practices series. Until then keep your lists clean and good luck.
—Source: iMedia Connection Feb 26, 2007 ( Spencer Kollas is director of delivery services for StrongMail Systems (