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Mastering Email Deliverability Part 1: The Fundamentals of Email Deliverability

Unleash the full potential of Klaviyo with a comprehensive audit!

April 23, 2024

By Alen Čapelja

Email metrics all start with deliverability, and you would be hard-pressed to find a more vital measure of success. In this first installment of our email deliverability series, we’re covering the foundational concepts and best practices you need to know to maximize every campaign’s opportunity to make an impact.

What Is Email Deliverability?

Email deliverability is a measure of how successfully the emails you send reach their intended recipients' inboxes rather than bouncing or landing in a spam folder.

Deliverability is so crucial because if an email isn’t delivered, all other efforts to make the email convert ultimately don’t matter. By ensuring your emails reach your audience's inboxes, you can drive up engagement, protect your sender reputation, optimize your marketing budget, and ultimately achieve your marketing goals more effectively. 

How Do You Calculate Email Deliverability?

Email deliverability rate is typically expressed as a percentage. To calculate it, divide the number of emails delivered to recipients’ inboxes by the total number sent and multiply by 100 to convert the decimal to a percentage.

Let’s say two companies send out an email newsletter to 1,000 recipients.

Company A’s email deliverability rate is 70 percent (700 emails delivered out of 1,000); Company B has achieved a much higher rate of 98 percent (980 emails delivered out of 1,000). The higher the rate, the better, but most companies are happy to achieve an email deliverability rate in the 90s. 

5 Factors to Consider: Best Practices for Email Deliverability

Why was Company B’s email deliverability rate so much higher than Company A’s? Many potential factors could be at play. Here are five best practices that help with deliverability:

1. Content  

In addition to influencing metrics such as open and click-through rates, the subject lines and bodies of your emails also influence deliverability. Internet service providers (ISPs) are on the lookout for anything that comes across as “spammy” or irrelevant to recipients. 

Avoid using language or tactics commonly associated with spam, such as:

  • Misleading subject lines
  • Excessive sales-oriented phrases (e.g., "buy now” or "free offer”) 
  • Overuse of capital letters and exclamation points

With nearly 46 percent of emails worldwide identified as spam, ISPs can’t be too vigilant about blocking harmful and irrelevant emails from their users’ inboxes. Focus on ensuring your emails deliver real value, not sales gimmicks, and you stand a much better chance of getting those emails to your target audience.

Learn more about the power of engaging email campaigns in our Leggari case study.

2. Design

Design can also play a role in deliverability. Emails should be easily digestible and viewable on any device. 

In 2018, the most widely used device for checking marketing emails was mobile, and the trend toward mobile has continued to increase since. Taking this into account, you must design your emails with responsive layouts that adapt to various screen sizes. Additionally, consider accessibility practices such as using alt text for images and ensuring readable font sizes to accommodate all users. 

The right imagery can help make your emails more engaging, but too many images can actually trigger spam filters. That’s because scammers often go heavy on images and light on text in an effort to bypass content filters. Make sure each image you include serves a purpose and doesn’t completely overshadow your text.

3. Sender Reputation

One major factor in determining email deliverability isn’t about the email itself but about who is sending it. ISPs want to protect their users’ inboxes from harmful or spammy content, and they can do so by blocking emails from suspicious sources. You can prove your trustworthiness in two main ways:

  • Maintain a consistent sending volume: Sudden spikes or irregularities in your email sending volume can raise red flags with ISPs, potentially harming your sender reputation. Start slow and aim for a consistent sending schedule that aligns with your audience's expectations and engagement patterns.
  • Avoid spam complaints: High rates of spam complaints can severely damage your sender reputation. To minimize complaints, ensure your emails are relevant, provide clear opt-out options, and respect users’ preferences and consent. 

Building a positive sender reputation takes time and consistent adherence to best practices. As you develop a positive reputation, you can expect to see a higher deliverability rate.

4. List Hygiene

An outdated or messy email list could be to blame for a poor deliverability rate. Maintaining good list hygiene can give you a more accurate understanding of your email campaigns’ performance and help you improve your email deliverability considerably. Invalid contacts will immediately result in higher bounce rates and lower deliverability. Plus, when you send emails to unengaged contacts, you’ll end up with lower open and click rates and possible spam complaints. ISPs take note of all of that and are more likely to suppress future emails you send to help keep their users’ inboxes free of unwanted junk mail. 

To avoid this scenario:

  • Remove invalid and inactive subscribers: Regularly audit your email list to remove invalid addresses (those that bounce) and inactive subscribers (those who haven't engaged with your emails during a defined period). Cleaning up your email list can instantly improve your deliverability. 
  • Run re-engagement campaigns: Before removing inactive subscribers, consider sending targeted re-engagement campaigns to win back their interest. These campaigns can offer special promotions, ask for feedback, or remind subscribers of the value your emails provide.

5. Authentication Protocols

Like a person’s signature on a letter or a barcode on a package, authentication protocols verify the authenticity of email senders so ISPs know the emails are from legitimate sources. Let’s look at three key authentication protocols for email marketers:

    • Sender Policy Framework (SPF): An SPF record lists all the IP addresses, domains, and subdomains your domain authorizes to send emails on your behalf. When an email is sent from your domain, the receiving server checks to ensure it’s coming from an approved source on the list.
    • DomainKeys Identified Mail (DKIM): Like putting a tamper-proof seal on your emails, DKIM uses digital signatures to verify that an email was indeed sent from your domain and hasn't been altered in transit. You’ll include a private key in email headers and publish a public key in your DNS records so receiving servers can verify a match.
    • Domain-based Message Authentication, Reporting, and Conformance (DMARC): DMARC tells email receivers how to handle failed email authentications (i.e., emails that don't align with your SPF and DKIM settings) and how to report these instances. For example, the email could be rejected or quarantined, or the email receiver could let it pass while reporting the discrepancy.

Many brands use a dedicated sending domain (also called a branded sending domain) intended only for email activity. This way, they can configure the domain with its own SPF, DKIM, and DMARC records to authenticate emails and can maintain careful control over their sender reputation.  

InLine CTA for blog content, Email Deliverability Series Part 2: Optimizing Email Sender Reputation and Building Trust with ISPs

How Can I Improve My Email Deliverability?

Email deliverability is foundational for executing any successful email campaign and for building a trusted brand reputation. There are some great tools and services out there to help you monitor and improve your email deliverability. For example, there are specific steps you can take within HubSpot and within Klayvio to track key deliverability metrics and proactively address issues that may be holding you back.

Want a helping hand? Our team can analyze your current email deliverability, help you set email marketing goals, and then work with you to achieve them! Get ready to build higher levels of trust and engagement with each campaign. Let’s get the conversation started!



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Topics: Marketing Strategy, Email Marketing, E-Commerce Marketing