According to MarketingSherpa, the average email list depreciates by 25% every year. To improve email deliverability you need to scrub your email list to reduce duplicate, invalid, dead, and bogus emails. Like a good spring and fall cleaning, scrub your list every six months to keep your email list healthy.

Follow these 9 tips for keeping a healthy email list:

Tip #1 – Don’t purchase lists. Don’t purchase lists from third parties. Sure, it has short term benefits but it negatively affects your delivery and sender reputation in the long-run. Recipients are much more likely to hit the “spam” button when they receive email from an unknown source. Very few good leads or good results come from purchased lists.

Tip #2 – Remove alias emails. Alias addresses are things like [email protected] or [email protected]. Many ESPs are not successful at delivering to these types of addresses because not all of the email addresses associated with the alias has opted in to receive communication from you.

Tip #3 – Keep your suppression list. List suppression means that subscribers have been added to the list because they have been unsubscribed, or emails sent to the email address have bounced. With these inactive subscribers flagged in your account as “suppressed,” it prevents any further emails being sent to them.

Tip #4 – Re-engage inactive subscribers. These are subscribers who have not responded to your email marketing in the past six months. By identifying these individuals, doesn’t mean removing them. First try to make them active subscribers by sending out an email that is specifically targeted to re-engage them. If there is no response to your re-engagement campaign, then take them off your active list, but keep the information in an archive of past subscribers.

Tip #5 – Purge unengaged subscribers from your list. Individual subscriber actions play a much bigger role in determining the overall deliverability of your list. While keeping a clean and well-segmented list has always been important, it has become more important to purge unengaged subscribers from your list.

Tip #6 – Segment your lists for targeted sends. Very large bulk (‘batch-and-blast’) sends can oftentimes be seen as spam. Targeted sends generally perform better (higher open rates and clickthrough rates), because it ensures you’re sending only the most relevant content to your subscribers which helps to improve your sender reputation.

Tip #7 – Remove bounces right away. Undeliverable emails (bounces) can mean the loss of prospects and customers that cost you handsomely to acquire. Some email address churn is normal, but database attrition associated with bounced emails can have a serious impact on your bottom line.

Tip #8 – Verify email addresses. Ensuring email addresses are accurate allows you to get your message delivered to the intended recipients. By verifying your email addresses you’ll achieve higher delivery rates by minimizing the number of invalid addresses, significantly better campaign performance, and greater revenue generation.

Tip #9 – Let subscribers edit their email preferences. When your email recipients click through to unsubscribe, offer them the opportunity to edit their email preferences. Allowing them to choose the frequency in which they receive email, and the topics about which they can be emailed, may save them from unsubscribing. Even if recipients don’t want to unsubscribe, include a link to this page in the footer of every email you send for greater personalization.

Mailing list maintenance is critical for marketing success. List scrubbing decreases unsubscribes and SPAM complaints; it helps you better segment your list and increase content relevancy; it improves your sender reputation, deliverability, and open rates; it saves you money; and lastly but most importantly, it keeps you legally compliant.