New Year’s cleaning? Spring cleaning?  Email list cleaning?

Building an email list is key for successful email marketing. Yet, while much focus goes into “How quickly can I grow my email list?”, businesses often neglect the other side of email list building & maintenance – “How can I make sure my email list is healthy and clean?”.


“A small list that wants exactly what you’re offering is better than a bigger list that isn’t committed.” – Ramsay Leimenstol

Poor email list cleaning practice tends to snowball catching brands off guard and negatively impacting sender reputation and email deliverability. When’s the last time you cleaned your email list?

This article covers the following topics on email list cleaning:

  1. What is email list cleaning?
  2. What are the benefits of email list cleaning?
  3. Why, when and how often should you scrub your email list?
  4. Email list cleaning best practice

Ready to dive in?

You’ve sent an amazing email campaign to your email list. But then… numbers roll in and the reality is not even close to what you’d have expected. 

Your marvellous email has either ended up in the dreaded spam folder or got exiled to a folder that rarely sees the light of day. Whatever the case, your brilliant campaign is lost forever. However, such a horrific fate can be easily avoided by maintaining a healthy, clean email list.

Email List Cleaning: Definition

Email list cleaning (a.k.a email scrubbing) is the process of regularly updating your email list by purging unengaged, outdated and inactive subscribers and, of course, honouring unsubscribe requests. 

Mailbox providers are getting smarter and more attuned to what recipients want to get in their inbox. Going through email address after email address to find the ones that have bounced or to pinpoint disengaged subscribers is extremely time-consuming. There’s no way around it unless… you use email marketing software that can automatically suppress contacts that have bounced which will help you maintain top-notch email list hygiene.

The Benefits Of Email List Cleaning

As the email list owner, it’s your responsibility to evaluate the cause of death – i.e. the drop-off in email marketing metrics such as open, conversion, engagement and deliverability rate. 

The top four common causes of email engagement death are – 

1) Silence Of The Lambs: You’ve left your subscribers hungry by not sending them emails.

2) The Pursuit Of Happiness: Chasing email happiness by sending nothing but promotional campaigns that do not create value for your target audience.  

3) Missing The Mark: You are sending emails that have completely missed the mark and do not resonate with your subscribers.

4) One Too Many: Your target audience is being bombarded with all sorts of emails (yours included) of which only a small per cent is relevant to them.

Now that we’ve cleared that out of the way, the benefits of email list cleaning are – 

  • better open, click-through and conversion rates
  • fewer spam complaints
  • fewer bounces
  • improved deliverability
  • reduced costs
  • higher revenue
  • better relationships with your target audience
  • protecting your most valuable asset: your data

Email list cleaning may seem like a pain, like any task involving housekeeping, but it will be worth the effort in the long run. 

Remember, an unhealthy email list can do immeasurable damage to your sender reputation and deliverability which in the long run will negatively impact your ability to reach your entire database (including your best and most engaged subscribers/customers).

Why Clean My Email List?

By the time you discover you have an email list hygiene issue, it’ll usually be too late. Your resources would have already been wasted and the whole ordeal would have done significant damage to your sender reputation and email deliverability. 

Do you know why you should clean your email list? 

Data Changes

Email lists naturally decay by around 25% per year. Some of the most common reasons are –

  • switching email providers
  • changing jobs
  • abandoning old email addresses
  • changed domain

Having a smaller email list is not something you should be bothered about or ashamed of. Quality always matters more than quantity and a smaller engaged email list is mightier than a huge disengaged one.

Unprotected Forms

Are your web forms protected? 

If you want to make sure the data coming through your web forms is that of actual real leads and subscribers rather than bots, spam traps or typos, why not consider putting an email cleansing API (data validation API) in place?

Why would you need such a thing? It will help you – 

  • reduce fraudulent or inaccurate data attacking your web forms, 
  • protect your deliverability and sender reputation,
  • improve your email campaign ROI, and
  • [on the front end] create a better experience for your audience. 

Spam Complaints

What are spam (email) complaints? A direct signal by email recipients given to mailbox providers (i.e. Gmail, Yahoo!, Outlook, Hotmail) that a given email is unwanted. 

No one likes a complainer. Especially when it comes to email marketing. Yet, complaints do happen – even to the best senders – and receiving some shouldn’t necessarily be considered as doomsday. The complaint rate can be an extremely powerful indicator revealing any blind sport in your email program. 

One of the crucially important reasons for email list cleaning is to avoid spam complaints.

Fewer spam complaints = fewer deliverability issues.

The top ways to prevent spam complaints are – 

  • setting up a custom domain
  • using double opt-in signup forms
  • keeping a permission-based email list
  • never buying, renting or borrowing email lists (they will contain spam traps!)
  • using a recognisable “From” email address
  • delivering relevant content
  • using personalisation
  • define and announce your email frequency

Pro tip: Your email marketing software will immediately unsubscribe recipients who submit a spam complaint from your email list and add them to your suppression list.

Email Deliverability & Sender Reputation

If your goal is an effective and successful email marketing program, email deliverability and sender reputation are paramount. Why? Your emails will be worthless unless they get delivered and your sender reputation determines whether or not they should be delivered.

A disengaged email list results in poor email deliverability and a falling sender reputation. Hence, if you don’t maintain a regular email list cleaning schedule, you are looking at a long list of avoidable issues and headaches.

If your target audience doesn’t like the emails you’re sending all it takes is the click of a button to report you as a spammer and for you to get “punished” for your poor email list hygiene by mailbox providers such as Gmail.

Inherited Email List

You started a new job and inherited an email list you don’t know much about. You have questions like “Where and how did this data ended up on this list? Is it purchased? Rented? Borrowed?”, “When was the last time this email list was cleaned?”. Yet, with inherited email lists, answers to such questions are a mystery. We’ve all been there once or twice.

Some marketers consider inheriting an email list a blessing since most of the list building work is done and they only have to focus on the creative part. However, it’s never that simple. 

The best way to find answers for all (and any) of your plaguing questions is email scrubbing. It will help you determine which emails are active and which ones are inactive. But… don’t rush and say “Ciao!” to inactive subscribers without trying to re-engage them first. You never know what might happen.

Purchased/Rented/Borrowed Email List

Email List Cleaning: What, When, Why and How | EmailOut.comIn email marketing, quality always, always, always comes before quantity. 

Let’s say your brand is just emerging on the scene or you’re about to launch a new product or service. How would you get the word around and promote if you don’t have a massive database at your disposal?  Hint: by not cutting corners and buying/renting/borrowing an email list.

Businesses selling email lists claim to have thousands of legitimate email addresses but the truth is… they do not. Buying an email list is a massive no-no because it can do your brand more harm than good. You have no clue what type of email addresses are in there just waiting to ruin your email deliverability, sender reputation and, ultimately, get you blacklisted.

Pro tip: Build your email list organically. Yet, if you made the mistake of purchasing or renting a list – or inherited one from your predecessor – email list cleaning is an urgent requirement. Organic lists less urgent, but regular maintenance should be scheduled in.

Avoid Spam Traps

Another vital reason why you should clean your email list is to identify and avoid spam traps. 

What are spam traps (a.k.a honeypots)? Email addresses solely created to capture spammers. Anti-spam organisations, Internet Service Providers (ISPs) and IP blocklist providers use them to lure spammers. Spam traps can cause your IP address – or even your domain – to be blacklisted/denied/blocked affecting your sender reputation and deliverability.

Pro tip: Use double opt-in signup forms. Sometimes email addresses can look valid but end up being bot signups or a spam trap. By asking subscribers to verify, you are playing it safe and ensure your email list is healthy.

Avoid Email Blacklists

Email List Cleaning: What, When, Why and How | EmailOut.com

An email blacklist is a real-time database put together by Internet Service Providers, anti-spam organisations, spam filtering companies and email service providers to protect subscribers from malicious emails.

It’s always a good idea to do a blacklist check. Not all email blacklists are equal. Being on Hunter’s All Things Fungi Blacklist’ is different from being on Spamhaus’s blacklist.

Why did you get blacklisted? Six reasons – 

  • your emails have been marked as SPAM 
  • poor email list hygiene
  • sending an abnormal amount of emails
  • spam complaints
  • bad email list database
  • poor email content

The best ways to avoid email blacklisting is to make sure you are delivering relevant, engaging, useful email content, monitor your email marketing KPIs for any spikes or unusual declines, email list segmentation and regularly email list cleaning.

If you are added to an email blacklist, the delisting process can take from a couple of days to a few weeks during which time your IP or domain will remain blocked and the level of harm that will befall you would have done potentially irreparable damage. So… clean, clean, clean.

When To Scrub Your Email List?

There is no definitive answer as to when to clean your email list. A rule of thumb (I came across in my research) is every three months. However, scrub it as often as you need to.

Now, check out the top 4 situation when email list cleaning is indeed a necessity.

Changing CRMs

Data + Email Marketing fits together just as perfectly as fish + chips.

Bad, “dirty” CRM data can – and will – negatively impact your email campaigns’ ROI, kill sales and, ultimately, waste your money. Actually, according to the world’s leading research company Gartner, organisations lose over $13 (£9.2) million yearly average on poor data.

Are you sitting on such data because you have no idea of its quality? Or, do you just like seeing big numbers in your email list counter?

There are four main reasons CRM data goes bad – 

  • outdated data,
  • poor formatting,
  • poor input, and
  • duplication.

When you are switching CRMs, it’s essential to double (even triple) check your database. A healthy, clean, organised and accurate email list is vital for personalisation and email automation.

Switching ESPs

For one reason or another, you decided to switch to new email marketing software. If your email program is small and relatively simple, the switch would be painless and easy. But… pain will ramp up pretty quickly if you have a massive database that is utilising personalisation (which it should).

The same troubles you will face when changing CRMs apply to switching ESPs. The solution is also the same – email list cleaning. Separating your active and inactive subscribers and removing ‘dead’ email addresses is key to effective email marketing and improving your ROI. 

There are three essential reasons why you should scrub your email list when switching ESPs – 

  • not transferring “bad” contacts,
  • keeping your reputation intact, and
  • quickening your warmup process.

Acquiring New Email Addresses

Every single time you collect new email addresses it’s crucial to ensure they are legitimate.

Use a double opt-in, take advantage of email checker online tools, etc. Deploy any – and all – online tools, best practice and resource you can think of to avoid any potential deliverability and sender reputation issues down the road. 

Running Re-Engagement Campaigns

A re-engagement email sequence aims to activate dormant email subscribers prompting them to get interested in your brand again and take action. Yet, before you start sending all those awesomely crafted We Miss You emails to the inactive subscribers make sure you’ve weeded out spam traps and other potential threats by scrubbing your email list first.

How Often To Scrub My Email List?

In an email utopia, your email list will always be in tip-top shape. But, we all know it’s neither as easy nor as perfect. Thus, just like cleaning your wardrobe for each season, you should clean your email list – regularly.

The email list cleaning frequency varies from brand to brand and email list to email list. How often should I clean my email list? is the lingering question on many email marketers’ mind. If you ask Google, timeframes range fromevery weekand as often as you needto once a year and neither is extremely helpful since it’s too general and not considering all the components of the quality of the data.

The best & most efficient way of determining the frequency of your email cleaning is to consider two main factors – 

  • the method used to collect the data (i.e. double or single opt-in forms), and
  • the type of email list: B2B or B2C (B2B lists require more frequent cleaning than B2C).

Pro tip: Implement real-time verification to your signup forms to prevent the entry of fraudulent email addresses.

Email List Cleaning Best Practice

Is there a point in sending awesome emails to stale email addresses? No, just let them go.

Once you’ve scrubbed your email list from the inactive, bots and bounces, the fun and creative part beings: improving communication with your target audience

Normally I go on and on and on with huge lists of best practice and advice. However, in this instance, I can summarise all email list cleaning best practice in a few bullet points (don’t want you getting bored).

  • start by email scrubbing your active email list
  • check your email lists regularly
  • always scrub your email list when switching ESPs or CRMs to prevent harm to your sender reputation and deliverability
  • monitor your email marketing KPIs and unsubscribe recipients who have not opened your email campaigns for two (or more) months
  • utilise email checker tools to double-check newly acquired email addresses (if they have not come from a double opt-in signup form)
  • utilise email cleaning tools to remove spam traps, inactive email addresses and typos
  • build your email list organically
  • never buy/rent/borrow email lists
  • use segmentation to help with re-engagement campaigns to inactive subscribers
  • use double opt-in signup forms
  • If all other advice is forgotten… remember to clean quarterly at the bare minimum.

Final Thoughts

If your email list is lacking a pulse, don’t waste time. Start assessing what’s gone wrong.

If you’re stuck and have no clue where to start with your email list cleaning, I hope this article has given you the necessary guidelines and solutions to maintaining a squeaky clean email list for the years ahead. 

Remember, be diligent in maintaining email list hygiene and frequently check and scrub inactive subscribers, bots, bounces and potential spam traps.

Highly recommended further reading – 

1) The Truth About Buying Email Lists
2) How to Improve Your Email Deliverability
3) How to Improve Your Email Sender Reputation
4) Email Automation 101
5) The Importance Of Email Whitelisting
6) Email Marketing Campaign Checklist (PDF version here)

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