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Boost your email deliverability with these 10 proven tactics

May 27, 2019 Gavin Sherry 6 min read

Email deliverability is, today, the number one challenge for many brands trying to communicate with their customers. The reason is that the major ISPs (Gmail, Hotmail, Yahoo etc.) and their definition of a good email sender, hides behind processes that feel more like “smoke and mirrors” rather than something prescriptive.

However, let’s start with something simple. Let’s agree on the objective of deliverability.

Email deliverability has just one clear objective; for your email to reach the inbox.

Well, that’s straightforward, right? However, if you’re looking at your delivered rate and it’s 99% and you’re thinking, “We don’t have any deliverability issues,” the chances are that you are kidding yourself. Sorry! The reason is that the IPSs are placing your email in two different locations, the inbox and the SPAM folder (junk folder).  

Emails going to the junk folder are still delivered. So, logical question, how do I know if my emails are going to the SPAM/junk folder? This is very difficult to assess. There are some third-party reports what can offer insights.

In my experience, these reports are not always giving an accurate assessment. However, there is one basic metric which you can rely on and that is a drop in open rates by ISP. This is your best measure if your emails are failing to hit the inbox.  

Time for a key consideration: The ISPs are not placing the email addresses of your ACTIVE base (recipients who have opened or clicked an email in the last 90 days) into the junk folder.

Like most things, prevention is easier than a cure. So, let’s look at some best practices. Here are my top 10 considerations:


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Avoid SPAM Traps

SPAM bots are actively targeting brands sign-ups. The output of this is that these spam bots which sign up are adding SPAM TRAPS to your list (more about them below). Hitting a SPAM TRAP is one of the worst things that can severely impact your deliverability reputation.

There are two solutions to mitigate such results. Firstly, include CAPTCHA to your sign-up process. Second, move your sign-up process to Double Opt-in. The impact of the latter may slightly reduce sign-up conversions. However, for the clients that do this, the quality of the new recipients is much, much higher. These are true fans of your brand. Nice!

Become an Unquestionable Email Sender

This is a requirement for all Exponea clients. It’s a series of records and validation reports (DNS, SPF, DKIM and DMARC) which confirm that the email sender’s domain is linked to your domain.  

Without these, you run a risk of someone else hacking your email account and sending dodgy emails to your list (can you imagine that!). With regards to the ISPs, if you don’t have these authentication processes you are a questionable email sender.  

Keep Your Mailing List in a Good Shape

Beyond suppressing or removing hard bounces and opt-outs, many clients are blind to the health of their mailing list. At Exponea, we can run a list validation service. This process “pings” email addresses with a simple API call. The recipient does not receive anything (in fact, they’re totally unaware of the entire process). However, the output is a validation of email addresses that are healthy and those that are “at risk”.

The Need to Segment

The number one reason why clients suffer from deliverability issues is that they continue to email everyone. The commercial logic of this is clear: the more you email, the more revenue you make. That’s not the case. There will be a significant proportion of your email list which have never opened or clicked an email (somewhere between 25% and 45% from my experience).

We need to accept that these email addresses add nothing to your revenue. Instead, this part of your list contains the most damaging deliverability issue, SPAM TRAPS. Spam traps are inactive email addresses.

For example, some years back I had a Hotmail email address. For whatever reason, I stopped using Hotmail. There is a distinct possibility that Hotmail has not closed my email account. Instead, they have left it open. If you email it, you’ve hit a SPAM TRAP.  To use a football analogy, it’s a bit like scoring an own goal (pretty bad!).

The fix is to segment your list according to ACTIVE email recipients, people who have opened or clicked in the last 90 days (or on a stretch, the last 180 days). This one recommendation typically resolves many deliverability problems.

Are You Emailing Too Much?

One of the main reasons why recipients’ emails end up in the junk folder is that you are emailing certain people too often.

When you “bombard” an email address when the recipient is clearly not interested (hasn’t opened or clicked an email in the last 180 days, for example) the most typical thing that happens next is that the ISP moves your email to the junk or spam folder.  

Only the most active email recipients should receive the most email. If you are emailing several times a week, you should link your email frequency to how engaged the audience are. So, only those that have opened or clicked in the last 30 days can receive 3+ emails a week.

Those whose last open or click is between 31 and 90 days, should receive 2 emails in the week. And yes, you’ve guessed it, people whose last open or click is between 91 and 180 days should receive only 1 email within that week.

Don’t Hide Your Unsubscribe Button

We need to accept that customers do “tune out” and will unsubscribe. It happens to all brands. Fact. But the requirement here is to make the unsubscribe link or button easy to find. To not include it or hide it away runs the risk of people reporting you as SPAM as a method for no longer receiving your email.

The difference to your sender reputation when a customer reports you as SPAM, compared to clicking the unsubscribe link is massive. SPAM complaints are a very negative “score” to you as a sender.   

One final point here, some brands ask many questions as to why customers are leaving on the unsubscribe page. If the process is too slow and painful, you run the risk of people reverting back to reporting you as SPAM. It’s one click.  

Ensure Your Email Looks Beautiful Regardless of the Device Or Email App

This is another factor where the ISPs will view you as not a good sender unless your email renders correctly. In the proofing stage, take the time to preview your email on all the major apps and devices.

Size Matters

Brands love to come up with very impactful emails. This is understandable, the email experience is one where the recipients typically scan an email before deciding if it’s of benefit to them. However, please be aware of email size. If your email is too large, much of it will be “truncated”.  

In Exponea there is a new feature notifying the user when the email size surpasses 102KB in size. The feature was created because clients were surpassing such size without realizing the risks and in general, not following best email practices.


Spam Content Is Not As Relevant As You Think

Many clients still think that “Spammy” content is the number one reason why their email might end up in the SPAM/junk folder. Yes, it’s still a factor. However, the health of your list, whether you segment your list and email frequency, are bigger factors (as discussed above).  

That said, you absolutely should still use a spam content scoring tool to advise if your email content poses any risks.

Starting from Scratch Is Not That Easy

And finally, for any email senders who believe that starting with a new sender domain / IP address offers them a clean slate, it’s not.  

The ISPs are starting to look at domain-based reputation. So, a history of bad email sending will catch-up with some brands. The solution again is to suck it up. When it comes to email, the ISPs are almighty and we have to keep them happy. Much of the above should help you manage that.


The fact is email still remains one of the top performing marketing channels. It’s cost-effective, yet capable of generating a high ROI. Unlike other marketing channels, it is mobile friendly, enabling your customers to access it through their preferred devices at any time.

Email become ever more powerful when it’s enriched with customer data and supported by other channels. With the help of current marketing automation technology like Exponea, brands can tailor highly personalized messages, optimize the email send time for each individual customer, and combine email with other marketing channels to create a personalized customer journey.

By following the above principles and with the right platform, you will not only boost the reach and impact of your email marketing, but also build trust and loyalty across your customer base. Which is, at the end of the day, the only thing that counts.

What Should You Read Next? Author's Hand-Picked Recommendation:

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meet the author
Gavin Sherry
Senior Deliverability & Strategic Consultant at Exponea
With over 20 years of experience in strategic marketing and e-commerce solutions, Gavin now serves as Exponea’s Senior Deliverability & Strategic Consultant, leveraging his expertise in digital marketing planning & implementation, B2B brand management, and email marketing. Specialties include: retail, travel, hospitality, financial services and IT.

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