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Everything you need to know about email deliverability and why it matters

September 08 - 2022

Email Marketing Strategy 5 min read

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Email deliverability is one of the most fundamental aspects of email marketing to get right yet, far too often, it’s an afterthought and is overlooked.

It’s time to change that.

Just pause for a minute and think how frustrating it is when something you’ve ordered or something you’re expecting to arrive isn’t delivered. It’s a nightmare and, if you’re anything like us, you’ll be sitting there thinking that there’s no excuse for something not being delivered when you expect it to be.

If a package didn’t get delivered when you expected it to, you’d do something about it. You’d be on the phone to customer services or sending an email to a help desk. You wouldn’t simply shrug your shoulders and accept it. Yet this tends to be the default setting when it comes to email deliverability.

It’s so easy to concentrate on all the glamorous aspects of email marketing - the design, the content, the smart segmentation - that deliverability (or the art of ensuring your messages reach your subscribers) is often overlooked.

And overlooking deliverability is something we all do at our peril.

The good news is - while it’s impossible to absolutely guarantee your emails will avoid spam folders or promotion tabs - there are some simple and hugely effective ways you can ensure your email marketing campaigns get the inbox placement they deserve. 

Let’s dive deeper into it…

What is email deliverability?

Deliverability is the measure of a successful delivery of an email to the recipient's inbox, instead of hitting a spam folder or outright bouncing.

ESPs (email service providers) report on delivery rates which are not the same. These metrics only look at bounce data to determine how many emails were successfully delivered to the recipient's server. The inbox placement rate is harder to quantify due to the variety of email platforms and their differing ways of dealing with spam emails.

Why is deliverability important?

We make it our mission to ensure our clients’ email delivery is optimised. 

All the effort of creating high quality, engaging email campaigns goes to waste if they don’t end up in the recipient's inbox. More emails landing in the inbox can only increase opens/clicks and conversions, which leads to increased return on investment and a better experience for subscribers. Everyone wins.

By making deliverability a priority, combined with a proactive approach to constantly monitoring it, performance and ROI can both be maximised.

What factors impact email deliverability?

Think of deliverability like this; you wouldn’t build an amazing new house on foundations that could easily crumble. By spending time building your foundations, ensuring your email sends are technically sound and encouraging your subscribers to add you to their contact lists, you’ll greatly improve the chances of your email marketing campaigns being read and, therefore, being successful.

The following factors of our ‘Deliverability Pyramid’ are what need to be in place to maximise email deliverability. 

A pyramid showing the 5 factors of deliverability.

1. Infrastructure

At the bottom of the pyramid, we have sending infrastructure. 

Your infrastructure is the ESP you use. Each ESP treats deliverability differently and - from our perspective - we need to consider the ESPs attitude and approach towards deliverability in order to make the appropriate recommendations if we feel this is unsatisfactory.

This is the first rung in the ladder because if this is not correct, then nothing afterwards will help.

2. Authentication

Email and domain authentication is, essentially, a way for email providers to know you are who you say you are. Although it might seem complicated, it’s actually a relatively straightforward process. The mail server receiving your email will look for your Sender Policy Framework (SPF) record and DomainKeys Identified Mail (DKIM) token. These records are added to your Domain Name Server (DNS) and, once they’re in place, the mail server receiving your email campaigns can verify who you are.

Think of it this way, a business called ‘RightMortgage’ sends an email campaign to its database from the email address When the campaign is sent, the receiving mail server will want to verify that the email is actually from RightMortgage. It does this by checking for the verification records mentioned above. If these records don’t exist, then there’s an increased chance the email campaign will go straight into the junk folder or won’t be delivered at all.

3. Data Quality

Data quality is a key component for email deliverability. ESPs will block anyone who has a high unsubscribe/complaint rate or if they continue sending to non-existent addresses. 

From a technical perspective, Captcha validation is essential for all web-based data capture forms to avoid spam bot data. Data validation tools, such as Validity, can also be used to improve data quality, particularly where there have been spamming issues or a licensed data from a third party source is being used.

There are simple ways to improve data quality like using engagement segmentation to suppress inactive and dormant emails from the regular sends. And the quest for higher levels of engagement shouldn’t stop there. With more ESPs taking open and click rates into account when determining spam, it’s even more important than ever to keep subscribers engaged and remove those who aren’t from databases. 

4. Volume & Frequency 

It’s important to keep regular send volume and consistent frequency. ESPs will look at the previous 3 to 6 months of volume to determine sending patterns and determine spam activity from this. For example, if a business doesn’t send any email campaigns for a number of months and then suddenly sends 100k emails, this looks like spam behaviour as past activity doesn’t corroborate with the current volume being sent. This may lead to emails being downgraded in the inbox.

5. IP & Domain Reputation

Finally, IP and Domain reputation are at the top of the pyramid. Think of it like an email credit score: If you keep up with your payments, the score will rise over time; miss any payments and the score drops.

Each ESP uses several different sources of information, including using AI tools to analyse the past behaviour of readers to your sends to define a reputation score. From this the likelihood of being placed in the inbox is determined. Measurements mailbox providers account for, but are not visible to us as marketers, include: 

  • Deleted without reading 
  • Filing (i.e. saving to another folder) 
  • Replying/forwarding 
  • Adding to the address book 
  • Retrieving emails from the junk folder 
  • Moving emails to the junk folder 

If any of the previous metrics takes a hit, then you can expect this reputation to take a few months to come back to normal. On the flip side, if the reputation score is low, then building the foundations on the lower levels of the pyramid will help the reputation score come back in line within a few months.

If all these metrics are in place and confirmed as working, it provides the optimum environment for good deliverability to flourish.

It’s worth remembering the mailbox provider’s priority is to their email account holders. So, creating relevant, engaging emails that the majority of your customers want to open and read, is vital in maintaining the overall reputation of your email and so the chance of reaching the inbox.

Check out this blog for more tips on how to take your email marketing engagement to the next level.

How do we monitor email deliverability?

We have a number of tools at our disposal to monitor, diagnose and fix any issues that we find.

We Litmus test each of our campaigns and use their features to double check that key deliverability statistics are in place prior to campaign launch.

Proactive reputation monitoring using Validity also helps us keep tabs on all of the above metrics for each of our clients. This is accomplished by aggregating direct reports from ESPs, regular seed list testing and domain (DMARC) reporting to give us a holistic view of a specific client’s deliverability.

Ready to get your email deliverability in shape and level-up your email marketing? Then we’re here to help.

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