Email Scrubbing – what is it and why do you need it

Verify Emails


Any good gardener knows that it isn’t enough to simply feed and water your plants to help them grow.  Pruning is an often-ignored part of maintaining the health of a garden. You cut away the dead and dying limbs so that only the strong remain and can flourish.

In this way, the email lists that we use to reach out to our customers are much like a garden. Far too often our focus is directly purely at feeding the list; always adding new names and email addresses. Feeding ensures that you have a large email list, but, much like an unpruned tree, it does not ensure that you have a healthy email list.  It is important to prune, or scrub, you email list to remove those contacts that are providing no value.  Services like Email List Verify make it simple to scrub your email list and ensure that your message is delivered to the right audience.

Why Scrub an Email List?

Because no one wants to be talking to an audience that isn’t listening.  While the exact number varies by industry, the national average open rate for email marketing hovers around 26% and click through rate at around 2.4%.  If your numbers look anything like that, then only one in every four recipients of your email campaign is even bothering to open it.  And of the people that actually open it, only one in ten engage it.

The goal of any email marketing campaign should be to get these metrics as high as possible.  It may seem implausible, but open rates as high as 45% are achievable.  Reaching numbers like this shows that your audience is engaged, your message is being heard and action is being taken.  By eliminating customers that you know are not interested in engaging with you, you can increase your click through and open rates.

Improved Analytics

Scrubbing contacts that aren’t engaged isn’t simply about making the numbers look better on paper.  While that may make everyone feel better, it doesn’t mean that you are getting more opens. The real value comes from the fact that removing unengaged contacts eliminates noise from the data you are collecting from your campaign.  It gives you better visibility to the impact of changes made on your campaign. 

For example, imagine you were A/B testing email subject lines. If all your unengaged contacts happened to receive subject line A, it would throw off your open rate data.  It would look like a significantly lower percentage of recipients were opening the email with subject line A.  When most of those recipients wouldn’t have opened the email regardless of the subject line.  If, instead, you removed the unengaged recipients, you might see that, of your engaged recipients, many more preferred subject line A.

Avoid Spam Traps

Email providers like Microsoft and Google are on a mission to deliver the best email experience for their customers.  That means filtering the deluge of emails that people receive every day so that only the emails that matter make it through.  Part of this is a stepped-up effort to cut out anything that is perceived as spam.

Every time someone reports one of your emails as spam, the odds increase that the email provider is going to make a rule that sends all your emails directly to the spam folder.  And unfortunately, that rule doesn’t apply just to the recipient that reported the message as spam.  If enough users flag up your message, that rule will be applied to all users of that specific email service.  Imagine never being able to send an email to anyone with an “@gmail.com” address without it going directly into their spam folder.  Your email marketing abilities would be severely impeded.

Save on Costs

Email marketing is extremely cost effective because of the ability to distribute a message to such a large audience for such a low cost.  But that doesn’t make it free.  Once you get away from one-on-one emails to individuals and move up to professional scale email marketing, you begin incurring costs for sending out emails.  Often the price of that service is determined by the number of contacts in your email list.  Why would you continue to spend the money to send emails to people that you know aren’t going to even open it? 

How do I use these tools?

There are two main ways that you can ensure you have high quality contacts in your contact database.  If you already have a contact database, then all you need to do is provide that database to an email list scrubbing service.  They will run the list through their algorithms to verify that the email addresses are valid and high quality and then return a clean list back to you.

Once you have a cleaned list or if you don’t yet have a list, then it is possible to verify the quality of the contact you are receiving prior to it being entered into your database.  This can be achieved through a web API that can be integrated directly into you web registration or newsletter signup form.  When someone goes onto a website and fills out one of these forms, the form knows to check with the email verification service before allowing the email to be entered into your database.  This ensures that the contact database remains clean.

What makes an email good or bad?

There are many different validation checks that are performed on each email address when a scrubber is attempting to qualify the address.

1.     Domain and SMTP – This checks the domain; the portion of the email address after the “@” symbol.  The scrubbing service can confirm that the domain is valid.  Invalid domains mean email won’t get through.

2.     Spam Trap – Spam traps are email addresses that don’t belong to real people and are used for no other purpose than trying to catch spammers.  The email address is never opted-in to any email marketing, so any that it receives must be spam.

3.     Disposable Email – Disposable emails are short lived emails that people use when the need to provide an email address but don’t want to provide their real email address.  Since these email addresses are meant to be temporary, you won’t have any success marketing to one of them.

4.     Catch-all Domains – Catch-all domains will accept email regardless of what is placed before the “@” symbol and redirect it to a specific inbox.  Spammers abused this behavior rendering these inboxes useless.  Now it is generally accepted that any email sent to a catch-all domain will never be viewed.

5.     Hard Bounce – Confirms that the email address can receive mail. There are several issues that could prevent messages from reaching an address.  A hard bounce check identifies any of the possible causes.

6.     Message Transfer Agent – This check confirms that the servers required for getting the email all the way to the desired recipient are in place and operational.

7.     Duplicate Removal – Eliminate any duplicate entries in your database.

8.     Syntax Errors – A real time check that can be provided if your signup form takes advantage of an API.  As a simple example, syntax checks ensure that the email follows the email address syntax of XXX@YYY.ZZZ.

When should I scrub my email list?

There are a couple different ways to tell if it is time to scrub your email list.  If you have ongoing email campaigns, then monitoring your open rates and click through rates can be a good way to determine if you need to scrub your list.  If you drop below the national average of 26% or below the average for your industry, then it is probably worth scrubbing your list.  Similarly, if you notice your bounce rate is climbing, that would be another indication that it is time to scrub your list.

If you don’t have API integration with an email scrubbing service for your web signup form, then it is probably a good idea to scrub your list every 6 months to ensure you are eliminating low quality contacts.

But for most people, the simplest answer is: if you have never done it, then you should do it right now.  Odds are there are some contacts in your email list that shouldn’t be there.

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