Email Security

Email Whitelisting: How To Increase Email Deliverability

Email Whitelisting lets your security tools know which addresses are known and trusted, ensuring that you’ll never miss an important email.

Email Whitelisting: How To Increase Email Deliverability

Email service providers want to ensure that users only end up seeing the emails that they want to see in their inbox. This means they need to successfully identify and remove spam or other nuisance emails from your inbox. For the most part, this is relatively easy to do. Emails that are sent out on mass, from senders who have low engagement rates are likely to be nuisance emails and can be removed. But it is not always that easy. To ensure that legitimate emails and senders are not considered spam, your email account will have a unique whitelist. This allows you to select specific accounts that can bypass your spam filters, meaning that you get the content from addresses you are interested in.

It is common for email marketeers to have their emails blocked if their content is deemed nuisance. This may be that it is sent too frequently, without the recipients properly responding to it. This is designed to save users from receiving mountains of spam mail.

In this article we’ll explain in more detail what whitelising is and go over how marketeers can improve delivery rates from their organization. In many cases, this is a result of consistent and thoughtful content that users are genuinely engaged with. Undesirable content is always going to be undesirable, and no amount of inbox priming or hope is going to overturn that.

What Is Email Whitelisting?

Your email provider spends a great deal of time investing in ways to tidy up your inbox. This tends to work by identifying desirable and undesirable mail. Spam emails can then be delivered to a separate inbox, allowing you access when you want it, without letting it get in the way.

Your email provider must find the balance between removing unwanted emails and permitting desired ones. Even if this assessment is only slightly wrong, it can result in important emails being missed and inboxes being flooded with spam.

Email Whitelisting is the process of marking an email address as desired. That way, your email provider knows that you want any correspondence from that user being forwarded to you. 

How Does Email Whitelisting Work?

Email Whitelisting works by informing your ISP that a specific email address is valued and desired. Once an address has been added to your ‘Approved Senders’ list, any correspondence from them will be allowed to enter your inbox, regardless of any other spam prevention policies.

Let’s take a closer look at how emails are delivered to your inbox, and how whitelisting factors into this equation.

When an email is sent, it will contain information relating to who the sender is within its header. This often includes IP address and other metadata. Email whitelisting takes this information, then checks it against any lists of approved or blocked senders. 

Any addresses that have been whitelisted can be redirected to a user’s inbox. Equally, any email addresses that feature on block lists will not be allowed through. As well as automatically blocking or permitted any emails based on header information, email providers will also consult Sender Scores. These are attributed to email accounts based on a wide range of factors, explaining how likely it is that an email is not spam.

What Are The Benefits Of Email Whitelisting?

Email whitelisting is the action of allowing a specific email address to bypass your spam filters, it’s as simple as that. In this section, we will outline how email whitelisting can benefit the recipient as well as the sender.

From a recipient’s perspective, adding an email address to your approved senders list (whitelisting) means that any correspondence from that user will automatically bypass any filters and land in your inbox. This means that you will never miss a message from this contact. If a user has taken the trouble of signing up to your correspondence, they won’t want their email provider to get in the way and block the content.

From the perspective of email senders, having your emails added to ‘Approved Senders’ lists not only ensures those customers can read your communication, but it improves your email deliverability overall. 

When a user whitelists an address, it shows email providers that you are a valued address and that your content is useful. This reassures them that your content is not dangerous (such as phishing content) or spam. Email providers will reward this valued content by improving your email sender score, resulting in improved deliverability.

Are There Any Other Ways To Improve Email Deliverability?

  1. Build your ISPs trust through sending small batches of quality content to engaged users. By sending content to users who engage with it, your ISP will trust that you are sending valuable content, rather than spam. This is sometimes known as inbox priming.
  2. Adjust your DMARC, SPF and DKIM records. These records confirm that emails from your brand are legitimate, rather than fraudulent. These three criteria help to reduce spam and phishing, whilst improving email deliverability.
  3. Improve your sender score. One of the main reasons why email sent to spam is due to a low sender score. This takes into account a range of factors such as number of spam complaints, how receptive subscribers are, and if you are on any blocklists to generate a score. Anything below 70 is considered low, while anything over 80 is considered a good score.
  4. Consistency is key. Rather than sending an irregular number of emails per week at a range of times, create a schedule and stick to it. When it comes to your sender reputation, erratic, infrequent, and unpredictable correspondence will get alarm bells ringing.
  5. Require users to double opt in. The fastest way to gather a large number of email addresses is through single opt-in policies. This means that as soon as a user ticks a box, they can be added to your senders list. This can, however, lead to a large number of complaints, resulting in a decreased sender score. When users have to confirm via email that they want to be included, they are less likely to report you as spam, ensuring that your sender score is not affected.


Email whitelisting gives users more control over which contacts are able to send emails to their accounts. It ensures that they receive every email from the accounts that they care about. 

If you run a blog with a newsletter, you may ask your subscribers to whitelist your address. This means that they will never miss a communication, whilst improving your deliverability score. This will have the knock-on effect of ensuring other users receive your communications.