What is email deliverability and how does it work?

When you work as an online marketer, the term 'email deliverability' will not be unfamiliar to you. Simply put, email deliverability describes the percentage of sent emails that actually reach their final destination. While marketers hope that this percentage is around 100%, in many cases, less than 80% of commercial emails achieve their goal. This can be explained by the increasingly effective filters designed to keep spam out of your inbox.

Marketing emails can quickly be marked as spam, causing the potential recipient to never read them. This is a waste of time and the return on investment of email campaigns. After all, large companies often pay per email address.

If only 20% of these email addresses are actually informed about your organisation's offers, the return on investment of such a campaign will be minimal. This is reason enough to investigate the factors that decrease or increase email deliverability. DKIM and SPF are two important tools in this regard.

In this article, we will tell you more about:

The necessity of eliminating spam

First and foremost, it is important to understand why the email deliverability of many campaigns has decreased significantly. This is mainly due to the fact that many people dislike spam. Spam is perceived as polluting and only leads to frustration among recipients. Not only will this prevent consumers from reading the spam, it can also give your company a bad reputation.

Spam is generally understood as an unsolicited and irrelevant message. The majority of spam is used by criminals, who may use spam to obtain sensitive data.

The proportion of spam messages in total email traffic has significantly decreased in recent years. This is evident from the decrease in the percentage associated with email deliverability.

Methods of recognising spam

The way email messages are marked as spam has evolved over the years. Previously, spam filters would examine the content of an email message to determine if it could be marked as spam based on keywords. The language and colour usage in the emails also played a role. Based on the number of points (the number of potential elements of spam) assigned to a message, it would be marked as spam.

The previously described point system is the first generation of spam filters. Over the years, these spam filters have become increasingly sophisticated. This is evident, for example, in the fact that a second-generation spam filter also looks at the sender's IP address. Based on the number of messages sent, it can be determined whether an IP address may be responsible for sending spam.

Although great strides have been made in recognising and blocking spam messages, you are likely still receiving emails occasionally that could be classified as spam. Conversely, email messages you want to read may also end up in your spam folder. This indicates that the systems are not always accurate in their operation.

Newsletters that may be relevant to a consumer can also be marked as spam. This reduces the email deliverability of a sending party, which in turn reduces the return on campaign investments. Therefore, it is important to explore ways to increase email deliverability for organisations.


Increasing Email Deliverability

Now that you have a simplified understanding of how email messages are labelled, it is important to look at ways to improve email deliverability. This is not only important for organisations when setting up marketing campaigns, but also for spam filters aiming to enhance the email deliverability of organisations providing valuable content to their consumers.

The focus is shifting from blocking bad messages to allowing good email messages through. This benefits organisations as it becomes easier to reach their target audience.

As mentioned earlier in this article, DKIM and SPF are two key concepts in this regard. Below, we will further explain what these concepts entail and how they can impact your email deliverability. These techniques focus on authentication, which will be one of the most important factors in allowing email messages through spam filters. The importance of good authentication will only increase in the coming years.


DKIM: Domain Keys Identified Mail

DKIM stands for Domain Keys Identified Mail, which is used for sender authentication. Unfortunately, you are not automatically protected against the misuse of your email address and the associated domain name. In many email programs, it is possible to set a custom sender address without actually owning that address.

This allows you to send emails on behalf of a different domain name, even if you do not own that domain. The software used to send spam or marketing messages can thus send a large number of messages on behalf of someone else. With this method, it becomes much more difficult for spam filters to determine which messages are genuine and which are sent by malicious senders.

This uncertainty decreases as more Domain Keys Identified Mail is used. With DKIM, it can be said with more certainty that the sender address of an email message is genuine. It can also be determined that the sender address is not being misused by malicious individuals. An important difference from standard spam filters is that DKIM does not analyse the content of the messages. As described earlier, standard spam filters do this using a point system. DKIM only looks at the sender of the email messages.

Often, email providers use multiple spam filters to assess messages. By implementing DKIM, a message can be passed through more quickly, unless the sender is suspicious. At that moment, the emails are also checked by a second spam filter for their reliability.

Overall, the use of DKIM will result in more emails being delivered. This also increases the email deliverability of campaigns and organisations. To avoid being marked as suspicious by the DKIM system, it is important to use an email address from your own domain when sending messages.


Precise operation of DKIM

Now that we have provided an initial introduction to DKIM and the benefits it offers, it is important to delve deeper into how it works. How can DKIM be implemented? How does a DKIM system verify the reliability of an email sender? First of all, an additional public key is added to the DNS of a server for the application of the DKIM technique.

DNS is essentially an address book containing all the settings of the domain name. This DNS is managed by the owner of a domain name but can be viewed by everyone. There are useful tools on the internet that allow you to retrieve the DNS information of a domain name without accessing the server.

It is not possible to simply add a random new key to your DNS. You need to contact your email provider and the organisation behind marketing automation systems. They can provide you with this key, which you can then add to a so-called TXT record of your domain name.

The process may vary depending on the domain name provider. Contact the domain name administrator to arrange this. Once this additional key has been added correctly, a fixed process is followed when sending email messages.


Description of how DKIM works

Is everything set up correctly? In that case, a signature will be added to each message sent from your server. This is not plain, visible text, but a 'hash key'. A hash key is a long, unique code that can link an email message to your identity. The hash key is determined based on the content of the email message and will vary for each message.

Now the message will be sent to the recipient, where it is initially blocked by a spam filter. The spam filter reads the key from your email and compares it with the public key from the DNS information. The key can now be validated or declared invalid. Based on the outcome of this test, the spam filter determines the next steps.

If the test is successfully carried out, the message can be delivered. The other anti-spam measures set by the recipient's server will be bypassed. If the test is unsuccessful, the message from the DKIM filter will go to another spam filter. There is a relatively high chance that the message will still be marked as spam. This does not bode well for the email deliverability of your campaign. Sufficient reason to set up this DKIM technique correctly.


SPF: Sender Policy Framework

Earlier in this article, two systems were already mentioned that can improve the email deliverability of your campaign. In addition to the DKIM filter, the SPF technique can also be used. SPF stands for Sender Policy Framework and serves as a second method to verify the authenticity of a message. If the authenticity is deemed reliable, the chances of an email being accepted are higher. This naturally benefits the email deliverability of your campaigns. Reason enough to also take a good look at this SPF technique alongside the DKIM technique.

Many companies use external systems to send email messages for marketing purposes. These systems are often referred to as marketing automation systems because they can send a large number of messages in a short period of time. This is not possible in most standard email programs.

The SPF filter checks whether a marketing automation system has permission from an organisation to send email messages on behalf of that organisation. It is possible that a malicious person may use marketing automation systems to send spam on behalf of others. These messages will not be delivered when the SPF filter is in use.

Operation of the SPF filter

The operation of the SPF filter is somewhat similar to that of the DKIM filter. In this case, a TXT record must also be added to the DNS settings of a domain name. This TXT record specifies which servers are allowed to send email messages on behalf of the domain name.

It is common to add the servers of the marketing automation systems being used to this record. If messages are sent from this system, the SPF filter will determine based on the DNS data that this is a legitimate action. This increases the likelihood that a message will be allowed through. This benefits the email deliverability of your campaigns.

However, there is also a disadvantage to the SPF filter. Using the SPF filter requires a very precise way of working. Especially in larger organisations, the risk of errors is high. After all, not only the marketing automation system should be able to use the domain name.

Even an email server on a mobile phone or tablet should be allowed to send messages on behalf of the domain name. If one of these servers is forgotten, it can result in messages not reaching recipients. This can be very frustrating for colleagues within your organisation, even if these are not marketing messages! This can understandably be very frustrating for colleagues within your organisation.

To prevent this from happening to your organisation, it is advisable to map out a complete landscape of servers in advance. Make sure all servers in this architecture are included. Once this is done, you can start adding the different servers to the TXT record of your domain name.

Select your campaign's target audience carefully

In addition to spam filters that can mark your email messages as spam, there are also recipients themselves who play a role in this. When multiple people mark your organisation's messages as spam, it can affect your email deliverability. It increases the likelihood that spam filters will immediately mark the email messages from your email address as spam. Moreover, it will not be good for your reputation if a large number of recipients block your email messages. Sufficient reason to carefully select the target audience for your messages.

Starting your own newsletter

There are several ways to find a suitable target audience. For example, offering a newsletter on your organisation's website can be a wise choice. When visitors sign up for this newsletter, they are likely to be interested in offers and news within your organisation. As a result, they are less likely to mark email messages as spam or rarely do so. Additionally, this is a legal way to obtain email addresses for sending messages.

Your organisation's newsletter should contain relevant information. Try to keep the amount of text limited and combine short summaries with attractive images. This increases the likelihood that newsletter readers will click on the various elements of the newsletter. Once on your website, you can encourage visitors to take action. Think about purchasing a product, requesting a quote, and so on. If you were to do this in your newsletter, it might come across as pushy. For a subsequent newsletter, this could then reduce email deliverability because readers may mark the newsletter as spam after seeing the pushiness.


Purchasing email addresses online

In addition to offering a newsletter on your organisation's website to increase email deliverability, you can also purchase email addresses. On the internet, you can find several websites offering large files of email addresses for sale. Keep in mind that these email addresses may not always fit within your organisation's target audience.

Therefore, make sure to carefully examine how these email addresses were obtained beforehand and whether the interests of the people behind these email addresses align with your organisation's services. There are strict rules associated with collecting email addresses. This makes it very important to investigate in advance whether a website selling email addresses has obtained these email addresses in a fair manner.


Various options for higher email deliverability

After focusing on various, often technical, possibilities to improve your organisation's email deliverability in this article, we list below a number of clear tips. Take these tips into account when preparing for your next marketing campaign:

  1. Start with two different campaigns
    Building a good reputation with ESPs, Email Service Providers (Gmail, Hotmail, etc.), is a first step towards higher email deliverability. These ESPs look at factors such as the number of emails opened by recipients. As the number of opened messages decreases, your reputation with ESPs will also decrease. This logically reduces the chances of new email messages reaching a recipient. To increase the percentage of recipients opening an email message, you can send two types of emails: a welcome message and an email based on recipient behavior.

  2. Find the right balance between long and short messages
    Each target audience may have different preferences. For example, younger people may be more inclined to scan a message for eye-catching headlines and beautiful images, while older individuals may prefer to scan longer pieces of text to see if a message is interesting to them. To find the precise balance between the length of an email message and your organization's target audience, it is advisable to conduct extensive testing. Do not do this directly for your entire email list, but rather select a small test group. Pay attention not only to variable lengths of email messages but also to variable times between sending messages.

  3. Ensure a clear subject line
    As mentioned earlier, the percentage of consumers opening an email message has a significant impact on the reputation your organization has with ESPs. It is wise to maximize the chances of messages being opened. One of the most important factors is the subject line of your message. Ensure that the subject line entices people to open the message without being too pushy.

    Above all, it is important that the information in the subject line describes what a reader can find in the rest of the email message. If the subject line deviates from the actual content of a message, it can deter readers. They may not open a subsequent message or unsubscribe from your newsletter.

  4. Clearly identify the sender of the email
    Equally important as the subject line of an email message is the sender. A recipient will always look at who sent the message before opening it to read the content. There are different ways to identify yourself as the sender to the recipient. You can choose a company name as the sender, but also your personal name.

  5. Encourage recipients to add your email address to their contacts
    To contribute to higher email deliverability in the future, it is important for recipients to add your email address to their contacts. However, it can come across as very intrusive when making this request in the first lines of an email message. It is wiser to use this request at the very bottom of an email message.

  6. Find the perfect message delivery time
    Several important aspects have already been described for structuring an email message. Think about setting the sender, coming up with a good subject, and so on. In addition, it is advisable to test the best time to send a message. This strongly depends on the target audience of your message. For example, an online store may best send a newsletter with discounts at times when consumers have time to view the discounted items. Think about weekends, or on weekdays after 5 pm. The best delivery time can vary greatly per company.

  7. Track recipients' activities
    With special tools for setting up email marketing campaigns, it is possible to track users' activities. Which users have opened the latest messages? Which users have been inactive for a long time? How have users clicked on the links in your newsletters? And so on. For the inactive members of your newsletter, you preferably want them to be removed from the list. This can negatively affect the percentage of recipients who open your newsletters. In addition, based on statistics on the most clicked links, you can see how to further optimize your newsletters for the future.

    To measure this, you use the automations 'Engagement Tagging part 1 and Engagement Tagging part 2'.


  8. Maintain interaction with your target audience
    Finally, it is important to be aware that contact with your target audience should not fade away. For example, make sure to send a new message to the members of your mailing list every once in a while to maintain interaction. It is strongly advised not to wait more than 60 days to send a new email message. If you don't have the time to maintain the email campaigns yourself, you can enlist an external party for this.

    Use the tips already described and the technical information from the first part of this instructional article to optimize your organization's current campaigns. An optimized campaign leads to better results and potentially higher revenue for your organization.
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