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A Guide to Email Deliverability Metrics

Apr 15, 2022

There are many factors that influence email deliverability. Some of these factors are things that email service providers can control, but many others are the sender’s responsibility.

So, when emails are not being delivered, it could be the result of bad sending habits that are putting emails in the spam folder or getting them blocked. Keep reading to find out more about why deliverability is important in emails, the metrics that have an impact on it, and some healthy email habits that you can develop to help improve your email deliverability rates.

What is Email Deliverability Rate vs Email Delivery Rate?

Email deliverability refers to the ability to reach recipients’ inboxes. It is also known as inbox placement rate or the percentage of sent emails that successfully end up in subscriber or reader inboxes.

This should not be confused with the email delivery rate, which refers to the percentage of emails that your recipients’ email servers receive.

It is possible to have a high email delivery rate while still having a low email deliverability rate since the emails are being delivered to spam rather than inboxes.

Why Email Deliverability Metrics are Important

The ability of your emails to land in the inboxes will depend on your standing with email providers like Outlook and Gmail. As a sender, you will build a domain reputation and sending reputation that will identify whether or not you are a genuine and trustworthy sender, or if your emails should be sent to spam.

Email deliverability will also affect the customer experience. For example, customers might become easily frustrated with your brand if they are getting password reset or order confirmation emails in their spam folder rather than their inbox, for example.

Factors That impact Campaign Deliverability

Making sure that emails reach the inbox every time depends on four main things – content, reputation, infrastructure, and authentication. These are all factors that both the sender and the email service provider are responsible for.

How Infrastructure Impacts Email Send Rate

The email infrastructure includes the framework such as the hardware and software that is responsible for making sure that emails are delivered successfully.

When an email infrastructure is reliable, this will consist of several systems that work together to accomplish it including feedback loops, IP addresses, SMTP servers, sender reputation management tools, and mail agents.

Sender Reputation Management Tools

This includes business intelligence and analytics tools that are used by email senders to monitor performance and ensure that the content and strategy are optimized to increase engagement by resonating better with recipients. These tools are used to track metrics like click-through rates, viewing recipients that are active or inactive, segmenting audiences, and monitoring IP reputation.

Mail Agents

This enables emails to be transferred, viewed, and replied to by both the recipient and sender. Different mail agents are used for each step of the email journey by a good email infrastructure.

Feedback Loops

These enable senders to get more information on spam complaints, and is a crucial part of email infrastructure. They allow senders to remove any recipients that have flagged them as spam to avoid further complaints and increase deliverability.

IP Addresses

The reputation of an IP address plays a key role in email deliverability.

Email Servers

These process and validate emails to be delivered to the subscriber’s inbox. Before this is done, the server verifies that the email is being sent to a valid email address from an active account with an acceptable sender reputation.

How to Ensure Email is Delivered – Authentication

Email authentication protocols such as DKIM, SPF, and DMARC are in place to assist mailbox providers in authenticating a sender and ensuring that they are who they claim to be. They look further than the ‘From’ email address and name in the header to verify that the message has actually been sent from the sending domain.

When you authenticate your domain, you prove ownership, which ultimately helps to ensure that email is delivered by making them less likely to bounce or be sent to spam.

How Email Reputation Impacts Email Deliverability Monitoring

Every email sender has a sender score, which works similarly to a credit score for your finances. This is a number that is assigned to your sending IP address by major Internet Service Providers and is based on various factors.

Some of the main factors that impact your email reputation include bounce rates, bounce rate frequency, email volume, and recipient interactions such as click-throughs and open rates.

Mistakes can cause the reputation that you have built over time to quickly disappear, which is why it is important to regularly keep on top of it. If your emails are suddenly going to junk or spam folders when you are monitoring deliverability, you might be dealing with a sender reputation problem.

There are several things that you can do to improve your sender reputation, including using a dedicated IP and adopting various good sending habits, such as regularly cleaning your mailing list to get rid of any invalid emails.

Along with this, it is also important to improve how you collect recipient emails and only send emails to recipients who have given you permission to send email to them, either by signing up for your services or buying a product, or opting into marketing emails.

How Email Content Can Impact Deliverability

The email content could be causing your emails to be unknowingly sent to spam or blocked. ISPs will consistently monitor and filter emails for malicious content and spam before they are cleared to go to the recipient’s inbox.

Spam filters look for clues like poorly formed HTML code, spammy words, and broken images and links.

It’s important to review your email content on a regular basis for anything that spam filters might view as a red flag, such as spammy words like ‘free’ or ‘act now’, writing mistakes, or image-only emails.

You can also use an email testing tool to check how likely the message is to pass through spam filters before you send.

How to Calculate Email Unsubscribe Rate

When you send marketing emails, there’s no getting away from the fact that some subscribers are going to change their mind. Whether they are just not interested in the emails that you are sending any longer or have signed up for your marketing emails by accident, unsubscribes are a fairly normal occurrence with email marketing.

However, it is a good idea to keep an eye on your unsubscribe rate since it can tell you a lot about the performance of your marketing emails. The unsubscribe rate will show you the percentage of users that have opted out of your email mailing list.

In some cases, subscribers opting out is not a bad thing, as it’s always better to have uninterested and unengaged subscribers off your mailing list compared to having them report your messages as spam.

To calculate the unsubscribe rate, simply divide the number of unsubscribes by the number of emails that have been delivered. Ideally, you should be aiming for around 0.5% or less, however, this can vary depending on your business industry.

How to Calculate Unsubscribe Rate – Why It’s High

If you have calculated your unsubscribe rate and it’s higher than you expected, there are several potential reasons for this. These are:

  • Different expectations – in some cases, it may just be that people expected something different from your email newsletter. This is a common occurrence if your signup form messaging is not consistent with the content that you deliver.
  • No segmentation – If you have not segmented your audience or have segmented incorrectly, then you might experience a high unsubscribe rate. You should only send email campaigns to people who are going to find the messages relevant.
  • Content formatting – Even if you are sending the content that your audience wants, if it is not easy to read on a range of devices, or is not loading correctly, then people are going to be more likely to unsubscribe.

How to Calculate Hard Bounce Rate

The bounce rate refers to when emails are not delivered. Typically, this results in a message being sent to the sender with an error code to explain the cause. Hard bounce refers to when the email address is invalid, or if your sender address or domain has been blocked or blacklisted.

Although there isn’t a definitive way of measuring the impact of a poor bounce rate, you can keep on top of it by calculating email bounce rates to see how many messages are not being delivered compared to the number of messages that you send. To work this out, divide the number of hard bounces by the number of delivered emails and multiply the result by one hundred.

Ideally, your hard bounce rate should be no less than 10%. Any higher, and you will be at risk of being blacklisted by popular email vendors.

Understanding email deliverability metrics and what impacts email deliverability is key to ensuring that your emails end up in inboxes rather than the spam folder.

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