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Improving email deliverability guide

Improving email deliverability guide

Improving email deliverability guide: The simplest question in email marketing might also be the one with the most complicated answer. As an email marketer, you want to provide killer content to your subscribers. You not only want to see people opening your emails – you want to see people engage with them in a meaningful way.
It’s about better positioning your campaigns to reach the inbox, avoid spam filters and then to get opened and acted upon by your subscribers. That’s where email deliverability comes in. What is email deliverability?

Email deliverability is how you measure the success of your emails reaching the inbox without bouncing or being marked as spam. If you have issues with high bounces, flagging spam filters or low engagement, you may have email deliverability issues. We’ll explore some quick, easy to implement fixes that you can use to help build your sending reputation and improve the success of your email campaigns.

Here is a list of 9 things that will kill your email deliverability:

Leaving your subscribers in the dark

Sometimes, old adages are true; prevention truly is better than the cure. In the email marketing world, this means first building a solid, permission-based list where your recipients have expressly opted-in to receive your emails.

But then, maximizing the potential of your subscriber list and the engagement level of your recipients requires more than just building a list of opt-in recipients – you want to start off on the right foot ensure it is unique and personal to that recipient.

If someone signs up to receive emails from your brand and they don’t receive an email for six months, they have probably forgotten who you are and why they signed up to receive your campaigns. In email deliverability terms, waiting too long to send your first email is killing your chance of creating a good first impression in the inbox.

Send consistently and regularly, though not too often. This can vary wildly depending on your industry and brand through one email quarter is probably too few, and one a day, too many. With some testing, you should be able to find a sending frequency that works for you and your subscribers.

Sending without custom authentication

A large part of email deliverability comes down to taking every step possible to avoid being perceived as a spammer in the eyes of spam filters and your recipients.

One of the most definitive ways in which you can affect this is by authenticating your emails. Authentication allows ISPs to acknowledge the legitimacy of your email sends. By putting verified SPF and DKIM settings in place, receiving mailboxes have some verifiable information to cross-reference with your email campaigns and can more easily determine if your email is the real deal or fraudulent. Gmail cites authentication as one of their top recommendations for helping get your email delivered to their users’ inboxes.

At SwiftERM, we automatically handle authentication for you, and by putting custom authentication settings in place, your emails are far more likely to be delivered.

Settling for single opt-in

Confirmed, or double opt-in means that after people select to sign up for your email list, they receive a confirmation email they must use to confirm their subscription.

Not only does confirm opt-in help protect you from erroneous sign-ups and spambots, but confirmed opt-in lists see better results with almost every engagement metric other than the sheer number of sign-ups in comparison to single opt-in lists.

Confirmed opt-in lists are more engaged from the start, and by using confirmed opt-in, you can more effectively build your sending reputation by sending to a more engaged and active list.

Sending from a free domain email address

Every part of your campaign needs to authoritatively communicate to your recipients and spam filters that you are who you say you are.

Using a “from address” that is a domain other than your own is a big no-no. Similarly, using a free domain email address such as Hotmail, Yahoo or Gmail is also a bad idea. Yahoo, Gmail, and other ISPs will automatically mark your emails as spam if you send commercial, or bulk email to an email address at their domain, from the same domain, under revised DMARC policies.

Instead, use an official company address that communicates who you are.

As a global brand with products and services spread across many industries, using a send-from address tailored to this particular part of the business is integral for strong email deliverability.

Be sure to use an address at a domain or authenticated sub-domain that you own and that your recipients expect to hear from. Not only will this help prevent ISP filters from blocking your emails, but this will also be instantly recognizable to your recipients and help build the sending reputation for your domain.

Using unclear or spam flagging subject lines

Your subject line is the welcome mat of your email and often issues with subject lines are as simple as this: if your subject line makes your email look like spam then people and the spam filters ISPs put in place to protect them will probably think that it’s spam. SwiftERM uses the title of the lead product; always different, stimulating and unique and impossible to be spam captured.

By using the correct subject line ensures that it matches the content of your email – no one wants to be promised a trip to a theme park and end up at the dentist.

Similarly, does your email require “urgent action” and is your offer “exclusive” and “one time only!”?

Best practices for the rest of your email copy also ring true for your subject lines.

Sending emails with too many images

A historic spam technique was to send emails that contain just one image, or many images and very little text in HTML emails to bypass spam filters that were based primarily on spam keywords.

Spam filtering is now based much more on sending reputation than content though image to text ratio does still carry some weight with spam filters and is something you will want to spend time getting right.

Emails with very little copy and many images, or simply composed of one large image can be hallmarks of spammers. By composing similar emails, you can run the risk of your email being flagged as spam. SwiftERM’s unique layout ensures the maximum impact from least spam capture.

Remember, many email clients or devices are not configured to display images by default.

SwiftERM emails are designed with this in mind and ensure you balance your images and copy so that your email makes sense and is engaging in the event of the images not being displayed. We always use alt text for your images so even if they don’t render, your subscribers will have context for what the images are.

Using URL shorteners

The use of URL shorteners is a notorious technique used by spammers to hide the nature of URLs they link to and as such, rank high on reasons spam filters can block your emails, even if the links themselves are legitimate.

We avoid using URL shorteners and also, avoid inserting the full URL link as text in the body of your email. Instead, we create a hyperlink with the appropriate text, ensure all your links go to legitimate domains and are valid and functional. By replacing URL shorteners with clear and attractive calls to action, you will also drive traffic and see more click-throughs on your sends. This is another piece of the sending reputation pie that can further boost your email deliverability.

Making it easy to unsubscribe

While an unsubscribe link must be included in every email sent through SwiftERM under GDPR, we also recommend that it be simple and easy for your recipients to find. Human behaviour is a curious beast, but one way for sure of proving to your customer’s that you respect them, is to provide them with a simple and easy means to leave whenever they like. Just because they can doesn’t mean they will. Indeed our studies on this exact point found a more positive attitude to working with retailers.

Hiding your unsubscribe link in a wall of text with an 8pt font will only serve to frustrate your recipients should they be attempting to unsubscribe. In our experience, the more difficult you make it to unsubscribe, the more likely your recipients are to simply mark your email as spam. Our unsubs link is displayed via “settings” at the bottom of every email.

Make your unsubscribe clear and easily visible and better yet, add a permission reminder message alongside it to remind people where they signed up or permitted you and point them towards unsubscribing if they are no longer interested in receiving your emails. Your recipients will appreciate this honesty and clarity and an unengaged recipient choosing to unsubscribe is always preferable to receiving a spam complaint.

Sending to unengaged recipients

In email deliverability terms, low open rates are a clear signal to ISPs that your recipients are not engaged with you, your brand or your content. That lack of engagement is a factor in the delivery of future emails and can even lead to campaigns being blocked. Think of it as a snowball threatening to become an avalanche – your low open rates mean that ISPs block your future emails, which leads to even lower open rates which in turn leads to a further lack of engagement. This is half the reason why promotional and marketing emails endure twice as high unsubscribe rate as SwiftERM. If you know your customer and what they like and server that master then you can enjoy the rewards.

Considering taking action with a list that you’ve nurtured and grown over a long period of time may be difficult, but what’s worse is this – you could be damaging your sending reputation by continuing to send to people who have never opened your emails and you are paying for the privilege.

Instead, send a re-engagement campaign to recipients who haven’t opened in over 12 months and check in on the engagement of your subscribers every 3 to 6 months.  Then, continue to personalize re-engagement campaigns to those dropping off in interest. Address the results in your database.

By amending your list so that it’s full of active recipients, you’ll see greater levels of engagement, and in turn, receiving ISPs will notice a higher volume of emails being opened and clicked compared to emails sent, which is super helpful to building and maintaining your sending reputation and positively affects your email deliverability in the future.


Email deliverability is an ever-changing aspect of email marketing and should be on the mind of every marketer. By implementing some of the recommendations in this post, and better positioning your campaigns for success, you should see improvements in the delivery of your emails and an improved ROI for your email marketing.

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One Response

  1. Before I read this article, I’d never really thought about deliverability of email campaigns. Really good thought leadership around the challenges of not just how to get your email read, but how to get an engaged recipient. Thank you!

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