The Pure360 Guide to Email Deliverability

Learn how and why email deliverability matters and is crucial to your email marketing strategy and results

What is email deliverability?

Email deliverability is the measure of how successfully you’re able to get your emails delivered to your recipient’s inboxes. It’s a simple concept, however terminology such as feedback loops, blacklists, and DKIM can become a little confusing and even daunting.

However, the reality is that if you follow simple best practice advice you shouldn’t have any problems.

Why does deliverability matter?

Your deliverability is arguably the most valuable asset your email marketing has. Without looking after it you may find that your emails aren’t being delivered to your recipients. To avoid all of your email marketing efforts going to waste, it’s important to get deliverability right.

What affects deliverability?

As you’ll discover, there is no exact science to getting your emails delivered to your recipients inboxes, and there is certainly no magic trick to getting it right. The reasoning for this is that ISPs such as Gmail and Yahoo are constantly evolving and developing new ways to protect their recipients from unsolicited spam. There are lots of different factors that ISPs look at, and to varying degrees it depends on the particular ISP.

Your data and how you collect it

The most important way for ISPs to determine whether to put your email into someone’s inbox, their junk folder, or simply not deliver it at all, is to look at how people have responded to emails from that sender before. Therefore the best way to ensure an inbox placement is to make sure that all of your recipients want to receive your emails.

Ensure that when people sign up, you’re as transparent as possible and are setting expectations of contact. For example, tell people what you’re going to send them and how often, so that they aren’t surprised when they receive your emails.

Offer recipients preference options when they sign up, for example they might not want to receive all of your emails, so have a preference centre in place that allows recipients to specify exactly what they want to receive from you.

You could also use a double opt-in email which asks recipients to verify their email address when they sign up. This ensures that the email addresses in your list are as legitimate as possible.

Lastly, make sure your privacy policy is publicised. Not only is this a legal requirement, but this will help people feel secure when they sign up.

Your sender reputation

Once people are signing up to your email list, keeping them engaged is absolutely key. Remember that in the eyes of ISPs, while everyone that opens and engages with your campaigns acts as a positive influence on your deliverability, people that aren’t engaging are dragging it back down. So make sure you’re doing all you can to keep people interested in what you’ve got to say.

Apart from your engagement levels, other important factors to consider that affect your reputation include:

  • Complaints – Even a tiny number of recipients marking your sends as junk can severely impact on your overall deliverability.
  • Bounces – ISPs will also look very carefully at your soft and hard bounce rates. If you send to addresses which are no longer valid this will generate a bounce. These are seen as a sign of poor list hygiene and could result in your sends getting junked.
  • Spam traps – These are usually old email addresses that are left active as ‘traps’ for marketers with bad data sourcing methods. Once emails are received, the sender is identified as one with bad data collection methods and is usually blocked by some or all of the major ISPs.
  • Sending volumes and consistency – ISPs prefer that you have a consistent pattern of sending. If you suddenly increase your sending overnight by a large percentage, or have a large spike in volumes after not sending for a week or two, it will probably result in inboxes being very wary of your sends and any higher rates of emails being deferred.
  • Blacklists – These are lists of either IP addresses or sending domains that have been previously identified as dangerous senders, usually through hitting spam traps or having high numbers of complaints.

Your content

Different ISPs look at the types of content that you’re sending in a variety of ways. Typically there are some key areas to watch out for:

  • Don’t link to websites that have been reported as sending spam in the past. Use a site such as to check this.
  • Ensure you’re not using link shorteners (for example,, as it will look like you’re trying to hide URLs.
  • Don’t send attachments, as these get flagged as dangerous, so link to them instead.
  • Some inboxes prefer you to have a 60/40 split of text to images. This doesn’t have to be exact; just make sure that you include some images and that they’re not touching each other in your html.
  • Ensure you have a plain text version behind your email.

Your ESP’s infrastructure

The last important factor is what Pure360 does for you. Our entire business depends on the successful delivery of large volumes of email. We have built a system that complies with the requirements of ISP best practice guidelines, giving you an extremely reliable platform for your email campaigns.

Your email will be authenticated with both DKIM and SPF technology. These tell the ISP that your mail has not been forged and is being sent from a verified source – Pure360. Compliance with DKIM and SPF positively marks your email in comparison to the spam that ISPs get from unauthenticated senders.

Depending on the amount of email that you send, Pure360 will make sure that your IP address setup is a perfect match for your sending pattern and volumes. As IP addresses are the main way that ISPs assign sending reputation, management of IP usage is important. Large volume email senders will have the benefit of sole responsibility over their own reputation by having a dedicated IP setup.

Pure360 are signed up for all ISP feedback loops, which allow us to easily unsubscribe your recipients who click the ‘mark as spam’ button. This helps you to avoid the spam folder because you are perceived as a sender whose mail is unwanted.

These are just some of the technical things which we do to make sure our platform works for you.

What to do if you have a deliverability issue

If your emails are being sent to your recipients’ junk folder, or not being delivered at all, there’s plenty you can do in your Pure360 account to determine why this could be happening:

  • Start by using one of Pure360’s inbuilt deliverability checkers. There are two versions, simple and advanced, both of which can be found within the ‘Preview & Testing’ tab in our visual editor. The simple version runs instantly, but only gives you an indication of any issues, whereas the advanced version sends your email off to Litmus for them to check, for a more detailed assessment.
  • Make sure you have a plain text version of your email. This is easily done using our visual editor. Just click the button that says ‘convert html to plain text’ and we’ll create one for you.
  • Test your email to a different inbox. Even if Gmail isn’t accepting your emails, Hotmail may still be, so it’s helpful to know how widespread the issue is.
  • Try changing the subject line of your email to something completely different to see if this changes your results.
  • Swap the subject line of your email out with some safe plain text. You can generate some of this to use on sites like If this results in your email being delivered, it suggests there is a problem with your html. If your email is still having problems, it could mean there is a problem with your sender reputation.
  • Try comparing your campaign to a previous one that you know didn’t have any issues, and swapping in some of your new content with the old content to see if this affects results.
  • Use a domain checker such as to ensure your sending domain doesn’t appear on any blacklists.
  • Make sure that your hard and soft bounce levels haven’t increased recently. If they have it’s possible that ISPs are viewing your sends as potentially dangerous.
  • If your sending volumes have increased recently it is possible that ISPs are rejecting some of the extra volume while they determine if your emails are safe.
  • If you are sending to purchased data or data that you’ve not contacted for a few months, you may need to re-engage recipients. Send them an opening email reminding them why they signed up and all the benefits of reading your emails.

You can find plenty more information about email deliverability online. When you choose to use Pure360 for your email and digital marketing campaigns we will work with you to ensure that your setup allows for you to achieve as high a level of deliverability as possible. Of course, it is up to you to ensure that you can keep these levels consistent. We offer such services as data health checks for your email lists, which we strongly recommend you carry out before sending your first campaign.

Read and discover more about email marketing on our blog

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