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9 Overlooked Aspects of Email Deliverability

9 Overlooked Aspects of Email Deliverability

Home Blog Digital Marketing 9 Overlooked Aspects of Email Deliverability

Love it or hate it – emails remain the undisputed, most powerful tool for business communication in the world. With over 4 billion global users checking their emails daily, there’s simply no room for debate on this matter. 

Chart of number of sent and received emails per day Worldwide

Just to put it into perspective, in 2020, there were 40 times more emails sent and received than the entire world population, so if you aren’t leveraging email marketing, you probably should.

Unsurprisingly, maximizing the effectiveness of email outreach has become a major topic of discussion over the years, yet not enough light is being shed on one critical component – email deliverability, email reputation and email marketing.

Email deliverability is the general understanding of how successful your emails are at reaching your recipients’ inboxes. Its significance is pretty straightforward- even the most perfectly-designed email campaigns won’t convert if they fail to deliver, and after all that effort, you’ll be left with no replies and no new leads. Nada.

A ‘no’ can become a ‘yes’ given the right circumstances, but if your emails fall into the web black hole – it’s game over. Bad deliverability will create a vicious cycle, further damaging your sender reputation, resulting in more emails going to spam – like a snowball slowly turning into a scary avalanche. Therefore, you have to make it a priority to improve your email deliverability as much as possible.

So let’s jump into some of the most impactful yet commonly overlooked aspects of email deliverability to make sure that doesn’t happen to us.

Proper Email Set-Up

Right off the bat, this is hands down the most crucial component of high deliverability, its foundation – skip it, and inevitably the whole thing will collapse. Email services expect adequate set-up and authentication from businesses to protect their users, and rightfully so, considering that 45% of all global emails are spam and 90% of cyberattacks occur via email.

The set-up infrastructure may seem overwhelming at first, which is probably why some businesses do it halfway or ignore it altogether, but there’s simply no way around it. 

So start with creating your own business email domain via an email provider ( Make sure you create several subdomains (, and try to stay away from free email addresses from Gmail or Outlook for mass/cold outreach if you want good email delivery.

Now it’s time to authenticate your email domain for credibility and security reasons with the following settings:

  • SPF (Sender Policy Framework)
  • DKIM (DomainKeys Identified Mail)
  • DMARC (Domain-Based Message Authentication, Reporting, & Conformance)
  • BIMI (Brand Indicators for Message Identification)

A quick Google search or asking for help from your IT team will get the job done in no time and will assure proper email authentication. Besides, many free tools can help with this mission. Skipping this step will guarantee a good chunk of your emails not passing through the gates of ESPs, never reaching your recipients and going straight to the spam folder.

Digital marketing campaign

Warming Up Your Domain

Now that you’ve set up your account, it’s time to warm up the engine before blasting out tons of emails. Email warm-up is the process of slowly and gradually increasing the volume of emails sent from your account to avoid looking suspicious and getting flagged by the recipients’ ISPs.

Nowadays, to successfully warm up an account, your emails also have to spark some form of engagement – get opened, replied to , marked as important, etc.

In case you’re wondering why you should even bother with this before sending emails, here are a couple of reasons:

It will build you a solid sender reputation – one of the most crucial factors of your deliverability rate and a determinant of whether email providers will let your emails through.

On top of that, warming up your account is by far the safest (if not the only) way to safely scale your email outreach. 

As businesses grow, so do their pools of potential and existing customers, meaning sooner or later, they will increase the number of emails sent daily.

You can expect the warm-up to last at least around a month. Here’s an example of a safe schedule to follow when warming up your email without setting off any alarm bells – aka spam complaint:

Example of a safe email warm-up schedule

Email warm-up can be manual, but the truth is there are plenty of great dedicated tools that can get the job done for you in a much faster timeframe.

Focusing on the Right Metrics

Your email is now battle-ready for your email campaigns. That doesn’t mean it will be a walk in the park from here on out. 

Marketers and salespeople are always on top of the important metrics regarding their email campaigns, constantly checking what works and what doesn’t, and ready to make the necessary changes if needed.

The only problem is that with new metrics appearing all the time, it’s hard to tell which ones should be paid attention to.

For example, while the open rate is a decent indicator of your campaign’s success, the open reach gives you a much more accurate representation. Open reach is the number of unique recipients that opened your emails over a given period of time, unlike the open rate, which simply shows how many times your emails were opened.

How to calculate your open reach rate

Another example is the inbox placement rate – email deliverability’s close cousin, that focuses on the % of emails placed in the recipients’ main inbox, rather than the general rate of emails delivered (which could still end up in promotions or go missing altogether).

For example, the graph below shows the inbox placement rate in blue, whereas the overall ‘delivery’ would be considered the blue + the red (spam), painting a much better, yet less relevant picture.

Focusing on the key marketing metrics allows businesses to accurately analyze where the top engagement comes from, and which areas they could work on to improve their deliverability before it’s too late.

Optimizing for mobile devices

Mobile devices account for the most global email views , even surpassing the classic computer.

Devices used regularly check email
Source: Adobe Consumer Email Survey Report 2017

The harsh reality is that 70% of recipients will delete your emails within 3 seconds if the message isn’t properly optimized and displayed on their mobile devices, 15% of whom will go a step further and unsubscribe.

So when businesses don’t take the time to optimize their emails for all devices, not only are they losing a huge chunk of potential revenue, but also harming their deliverability and sender reputation. Capping your subject lines at 30 characters, using pre-headers, and placing the CTAs as the center piece are a few good ways to get the ball rolling.

The more people that unsubscribe from your email newsletter – the more harmful it is to your sender reputation, which will undoubtedly lead to lower deliverability in the long run. Taking that extra step in making your emails responsive for phones will increase click rates by 15% and keep your email deliverability nice and strong for future campaigns.

Maintaining Your Email List

Growing your organization’s email list is important, but not as important as maintaining it and keeping it healthy. To do so, you should continuously remove unengaged, inactive, or worse of all – fake addresses from your email lists. Not only will this bump your sender reputation, but also score you brownie points in email delivery and inbox placement.

How often one should scrub through their email list is up to them, but keep in mind that, on average, they naturally shrink by 25% annually throughout the ‘email subscriber lifecycle’.

The email subscriber lifecycle

Email bounces are inevitable and impossible to predict, but what you can do is remove all the hard and repetitive soft bounce addresses from your lists. Inactive subscribers simply do more harm than good.

Another point to consider is that around 20% of all email signups have some sort of typo or other problems present. Solution? Validate all new email addresses from time to time to cut off the fakes, duplicates, and invalid ones from your precious list.

Yet, the biggest sin of email marketing is buying email lists. Yes, it’s a fast and relatively cheap way of acquiring tens, hundreds, or possibly thousands of email addresses for your campaigns. But how many of those addresses are fake or spam traps? How many are addresses of people that are anything but interested in your content?

This is honestly one of the easiest and fastest ways to permanently ruin your sender reputation and email deliverability.

Segmenting Your Email List

While we’re on the topic, segmenting your subscriber list is a proven marketing strategy that will unquestionably boost your email deliverability.

List segmentation can increase the total revenue

By doubling down on personalization and the relevancy of your emails, you’ll be doubling down on maintaining an engaged email list of subscribers who love your content. Once split into separate groups, you can create customized, hyper-effective email campaigns with unique content, subject lines, schedules, etc., that best suit that specific audience.

Considering that 88% of email users are more likely to engage with emails that deliver some form of personalization, I’d say you’ll be doing yourself a huge favor.

Making It Simple to Opt-Out

What’s that cliché phrase? Don’t force someone to stay – if they really want to, they will? Well, with your email subscribers it’s a similar story, perhaps a tad less dramatic.

This is a common mistake marketers make, thinking that the more difficult they make it for subscribers to leave – the better. This couldn’t be further from the truth. Quite the contrary, actually.

Instead, you should make it ridiculously easy for them to unsubscribe whenever they feel like it instead of hiding that clickable function, along with a tiny font size.

Unsubscribe example email

It’s much better for folks that aren’t that interested in your emails to unsubscribe rather than them hitting that scary spam button. Well, making it difficult to unsubscribe will frustrate them enough to do exactly that, hurting your sender reputation along the way.

It’s also imperative to make the opt-out link visible and accessible to comply with federal laws , as it would be illegal otherwise, according to the American Federal Trade Commission.

Similarly, only qualifying and emailing marketing prospects, that explicitly confirm their interest with double opt-in, may shorten your email list, but it (fake signups) will prevent them from hitting that spam button at some point in time, harming your email deliverability.

Constantly Improve Your Campaigns

Every industry and target audience has different preferences, so when businesses create their email campaigns set in stone, it’s a huge gamble. 

It’s best to leave room for flexibility and A/B test all your email efforts to find the sweet spot – how often, how many visuals, and which days work best for you.

Although it depends on your industry, our research concludes that Mondays and Thursdays between 07:00 and 10:00 AM are the golden time slots for engagement, while weekends are a bit tricky.

While the difference among weekdays is marginal, if we’re talking about thousands of recipients – that can be a huge difference in terms of engagement (hence deliverability) and even revenue.

A little bonus tip – aim to send your emails on a recurring schedule (same days of the week, same time). It’s a pleasant little boost for your inbox placement as your recipients will be more likely to engage with anticipated emails.

Content, Content, Content

We can discuss all the tips, tricks, and best practices for avoiding spam filters and sparking engagement, but without truly great and valuable content – email deliverability is doomed. A great rule of thumb here is pretty simple – don’t send out content that you yourselves wouldn’t want to receive.

First impressions matter, which is why 69% of email users send an email straight to spam solely based on the subject line, so don’t neglect it!

Avoid clickbaity and gimmicky content at all costs. It may yield better conversion in the short run, but unlike providing value to your recipients – will definitely backfire at some point in the future.

Another thing is, even though you’re not spamming doesn’t mean you shouldn’t pay great attention to spam filters. There are hundreds of spam trigger words that will prevent your emails from ever reaching the inbox, even with the best intentions at heart and a solid sender reputation.

The same applies to infographics. While emails with some form of visuals produce higher open and click-through rates, experts recommend keeping an 80/20 text-to-image ratio and avoiding emails with no text at all.

Email providers are great at detecting and blocking spammers, but are not perfect (yet). Gmail, for instance, blocks over a staggering 100 million emails daily ! Therefore, it’s probably a good idea to verify that your email content complies with all the regulations to avoid being part of that statistic.

Digital marketing campaign

Wrapping Up

Email marketing revenue will be just short of 10 billion by the end of this year, and it looks like it will keep growing in the near future. And even though spam filters are getting more thorough and precise, email deliverability will remain an ongoing battle for organizations that may end up being innocent bystanders.

Marketers should pay close attention to their email campaign’s deliverability metrics so that all the joint team efforts don’t go to waste. The good news is that by following the above-mentioned best practices, it’s in our hands to make sure our emails reach our beloved subscribers’ inboxes, improving the marketing ROI and helping the business grow.

Paired with some of the great tools created to help set up personal domains, validate emails, warm up accounts, A/B test campaigns, track engagement, and even automate your entire email outreach – your email campaigns are destined for great success.

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Olga Zamiatina

Olga is leading the Deliverability team within the Customer Success department at Reply. For the past 5 years, she has been helping the users maximize their inbox placement and resolve related issues with their outreach campaigns.

Deliverability Manager