Your complete guide to email deliverability
For email marketeers, deliverability is increasingly coming under the spotlight. ISPs are clamping down against spam, and adding new restrictions on access to customer mailboxes. Great news for the user, as it helps to minimise inbox clutter.
But, from a sender’s perspective, it becomes ever-more challenging to ensure that important communications are still landing in the right place, and that relevant emails aren’t being missed by customers.
Yet many of the deliverability issues which arise are down to silly mistakes, or inexperience on the part of the sender. Fortunately, we’ve put together a comprehensive guide below to help you get on top of your game in 2023.
What is email deliverability?
Email deliverability is a metric which quantifies the proportion of marketing and/or transactional emails successfully arriving in recipients’ inboxes (also known as ‘inbox deliverability’). Sounds simple, right? Nevertheless, it’s important to distinguish between email delivery and email deliverability, because these two terms are not interchangeable.
Email delivery is essentially the first stage of the process – you firing off the email; the recipient’s mail server accepting the email file; and then presenting it to the mailbox.
The second stage of the process is where the email actually ends up – for example, in the inbox, spam, or any other folders which are tucked away from plain sight. As such, deliverability focuses specifically on whether emails end up in the customer’s primary inbox or not.
What affects email deliverability?
To help pinpoint the causes of deliverability problems, it’s useful to have a basic understanding of the process behind an email send:
Outbound mail server sends the email
Email reaches inbound mail server via an internet connection
ISP decides whether to authenticate the email based on sender reputation
ISP either blocks the email, or directs it to the folder deemed most suitable
A common reason why emails never reach their intended destination is due to email bouncing. This could either be due to a ‘hard bounce’, which occurs when the recipient email address is invalid. Based on the above list, you could say that, in the event of a hard bounce, the process doesn’t reach step 2.
Alternatively, it could be due to a ‘soft bounce’, whereby it gets stuck at step 3. A soft bounce occurs for various reasons such as the recipient’s inbox being full; email content infringing on ESP policies; the sender address being on the ESP’s blocklist; sending too many emails in a short space of time; or the email being too large.
The next line of defence are spam filters - and again, there are a number of reasons why an email ends up in this dreaded wasteland. The most common causes are the recipient marking your email address as spam; having a low sender score; or content which raises a red flag (in particular, the subject line). It’s also crucial to avoid spam traps – sending just a single email to these fake accounts can result in ESPs blacklisting you.
But getting past spam filters and blacklists isn’t the final hurdle. Even then, ESPs such as Gmail or Yahoo have folders separate from the inbox (eg: Updates, Social and Promotional) – folders which seldom get checked by the recipient (at least on desktop anyway). So it becomes increasingly important to have a strategy in place to ensure you don’t fall foul of the algorithms these ESPs use, and that’s what we’ll cover in the next section.
How to improve email deliverability
We could probably write a book about this, as there are so many different steps – big and small – which you can take to boost your email deliverability. But to ensure you keep a laser focus on the path to success, here are five quick wins to prioritise…
Build your own reputation: Two key elements which affect your sender score are IP reputation and sender domain reputation. Many businesses use shared IP addresses, and then use variations in the domain names to differentiate themselves. This is beneficial from a cost perspective, but it can leave you vulnerable to weaker email deliverability if others sharing your IP don’t follow best practices. That’s where a dedicated IP can help to increase your deliverability reputation – just be mindful that it’s expensive, and you will also need a bit of time to warm up your IP.
Review your subscriber list: ISPs put a lot of emphasis on whether users interact with emails, so if a customer has become disengaged, it is self-defeating to keep hammering them with emails. Every now and then, do a clean-up of your subscriber list. Better yet, segment users based on their level of engagement; overlay this on other segmentation such as preferences; and then decide how often to email each group.
Use a double opt-in: Using a double opt-in for subscribers won’t improve email deliverability of itself. However, it can be helpful on two fronts: firstly, customers who go through a two-stage process are more likely to want to engage with the email content you send. And secondly, it helps to filter out invalid email addresses.
Optimise content: Optimised content starts with the subject line. First and foremost, make sure you avoid any obvious triggers that come across as spammy, and don’t overdo emojis and slang. Personalising the ‘From’ field with credible company branding goes a long way too. As for the body content, it’s important to make it as personalised and relevant as possible. There are also a few other considerations like the length of the email, the ratio of images to copy, and ensuring that emails are mobile-friendly. Finally, users and ISPs tend to respond well to a regular schedule of email sends, so try and follow a consistent pattern.
Monitor your progress: Maintaining strong email deliverability is every bit as important as achieving it in the first place. Most customer engagement platforms have tools such as tracking pixels, which provide detailed metrics so you can keep a close eye on things. It’s also worth making use of feedback loops to gain valuable insights. Ultimately, gathering and analysing all this information will help inform decisions on sunset policies, targeting and personalisation based on reliable data – a cornerstone of deliverability best practice.
