We published an updated version of this blog post on 5 May 2022. 

How clean is your email database? Have you ever considered cleaning it up to make sure you’re interacting with active subscribers? The practice of email list hygiene is essential for improving your sender reputation, and ensuring your emails aren’t automatically marked as spam.

Data errors can creep into your mailing lists at any stage during a list-building campaign. It is best to check for invalid and duplicate email addresses, and ensuring unresponsive contacts are removed from your database. We recommend cleaning your database on a quarterly basis to improve your chances of successfully reaching your subscribers inboxes.

If you’re curious about what causes “dirty data, here are some factors:

  • Duplicate records.
  • Stale or incomplete data.
  • Improper data collection methods.

Did you know that email service providers calculate how many of your subscribers open and click links within your email, unsubscribe, or are inactive? They use this information to determine whether you’re a spammer, which could result in being blacklisted.

So how does list hygiene help? A thorough, consistent list hygiene practice will lead to finding the following negative aspects of your lists:

  • Sender reputation threats (e.g. spam traps, honey pots, etc.)
  • Inbox delivery threats (e.g. bots, spammers, spelling errors, etc.)
  • Customer conversion threats (e.g. false usernames, profanity, etc.)

Now that you understand the importance of good list hygiene, let’s take a close look at how to maintain a clean list.

List Hygiene Best Practices

Here are a few simple steps you can use to make sure your email list remains clean from the start.

  1. Don’t Ever Buy an Email List

This is a one-way ticket to getting marked as spam, or blacklisted. It’s illegal to send unsolicited email in many countries, and South Africa has specific laws prohibiting this practice. Don’t do it. Not even once.

  1. Clean Up How You Collect Emails

Collecting email addresses can be a daunting task, especially in light of the POPI Act and its laws against sending unsolicited emails. In terms of list hygiene, there may be cases where you are given an email address on a business card and it needs to be captured manually. This could lead to an error if spelled incorrectly.

To ensure the incorrect email address isn’t causing reputation issues, validate all new your email addresses by sending confirmation emails to your new contacts to remind them of who you are and why they subscribed to your list. Most subscription form services will have this as an option, we recommend that you use it.

  1. Scrub Out Bouncing Email Addresses

Bounce backs are an important warning sign that something has gone wrong in your email process. They let you know when an error has occurred with your contact’s email address. Most email marketing programs have pre-determined methods for automatically dealing with bounced emails. These systems handle soft and hard bounces differently:

  • Soft Bounce: The system may try to re-send an email. Usually there’s a bounce limit set, based on number of bounces or a period of time during which the mail consistently fails. Once the bounce limit has been reached, the system will stop sending mails to that email address.
  • Hard Bounce: Most email marketing systems will automatically suspend an email address that returns a hard bounce. This is to avoid developing a bad reputation with the ISPs and possibly being marked as a source of spam.

We recommend against deleting contacts who have been set to an inactive status due to bounces. If you do so, you run the risk of re-importing them at a later stage and sending to them again.

  1. Segment Your Email List Based on Contact Engagement

List segmentation lets you partition your contacts into various categories:

  • Contacts who are opening and clicking your emails into a list of active subscribers.
  • Contacts who haven’t interacted with your emails in 6 – 12 months. This is a great opportunity to run re-engagement campaigns to try and get these potential customers interested in your brand again
  • Contacts who haven’t engaged with your emails in 1 – 2 years. You can send them a re-confirmation email asking them to opt into your mailing list again. If they don’t, keep them separate so that you don’t accidentally send them emails they don’t want
  • Choose a cut-off point for those contacts who haven’t opened or clicked any emails in more than 2 years. They are clearly not interested and should be unsubscribed from your list
What to Do When Merging Lists

Merging lists creates an opportunity to ruin your carefully cleaned mailing list. You risk importing duplicates, role accounts (help@, admin@ etc), and possibly re-importing someone who has opted-out of your mailing lists.

Always re-apply list hygiene practices to all lists that you merge, removing duplicates so contacts only exist in the final list.

In Summary

Proper list hygiene can be time consuming if your list is in a bad state, but it is worth it in the long run. Clean email lists perform better, giving you higher open and read rates, and a far better return than sending to uninterested, or non-existent contacts.

Check out our email marketing offerings here to make list segmentation easy with our comprehensive suite of station and reporting tools.