Brands are more than a year into dealing with the reality of Gmail and Yahoo’s new spam guidelines, yet persistent deliverability issues are keeping many, many of the companies we talk to on the wrong side of the spam thresholds.

We’ve had so many conversations with frustrated brands that we figured we might as well make our solutions available in written form. Below, broken out by subscriber acquisition, execution & strategy, data & reporting, and email development (with a bonus glossary of terms at the end), is our approach to keeping clients’ email campaigns right where they should be: user inboxes.

Subscriber Acquisition

Email deliverability issues often arise from engagement challenges, domain-specific spam filtering, and inadequate audience segmentation. Some clients have experienced email deliverability issues – particularly with Gmail and Yahoo, which account for over 70% of our publisher volume. Identifying these issues requires account-level work to analyze engagement data, monitor spam complaints, and leverage tools like Litmus Spam Testing and Google Postmaster.

To mitigate complaints, we recommend focusing on improving opt-in clarity, striving for real-time welcome emails, and using validation filters like FreshAddress and EmailOversight. It’s also important to refine segmentation by incorporating past purchase behavior, email interaction history, and engagement frequency. Defining clear engagement thresholds for acquired subscribers—such as 3-5 non-engaged sends—helps identify when to reassess communication strategies and avoid sending to inactive recipients, ultimately boosting deliverability.

Implementing suppression strategies at the domain level is also helpful to maintain a clean, healthy list. Additional tactics for improving deliverability include adjusting segmentation or the content strategy.

Execution & Strategy

To achieve strong email deliverability, it’s essential to follow best practices in authentication, segmentation, list hygiene, and content strategy.

• Use a dedicated IP and follow domain authentication protocols (DKIM, SPF, DMARC, BIMI) to help sender reputation and inbox placement. Make sure you’re dedicating time to staying informed and adapting to new authentication measures as industry standards evolve.
• Set up appropriate segments and exclusions to target audiences to reduce potential spam complaints and increase engagement—improving sender reputation and overall deliverability.​
• Maintain a healthy email list by routinely removing inactive/invalid contacts. Re-engagement campaigns can help to win back unengaged subscribers, while sunset flows can be used to remove persistently inactive contacts.

Recipient engagement is a big factor in determining email deliverability, so it’s important to ensure that email content is engaging, relevant, and optimized to get past spam filters. ​To help create this content, we recommend using behavioral data (email engagement, website clicks, purchase history, etc.) to create highly personalized messaging for segments and improve engagement. We also recommend you implement A/B testing to identify what’s performing well — which will give you good insights for current and future email strategies.

Data & Reporting

To measure, monitor, and report on deliverability, we rely on key metrics, including deliveries, sends, spam complaint rates, bounce rates, and bounce types (hard, soft, unknown). Examining domain and device distribution can also be revealing.

Hard bounces result from invalid or inactive email addresses, while soft bounces occur due to temporary issues such as full inboxes or server problems. To maintain list health, hard-bounced addresses should be removed.

Reports, queries, and data extracts from ESPs can be used to monitor these deliverability metrics. In addition, seed lists (lists of email addresses that you send emails to before sending them to actual subscribers) can be used to monitor and test the inbox placement of emails.

To ensure optimal email deliverability and maintain a healthy subscriber list, it’s crucial to regularly analyze these metrics and implement necessary adjustments accordingly.

Email Development

Optimized coding practices are essential for maintaining deliverability and providing a seamless and accessible user experience. Some helpful coding considerations include:

• Utilizing a DRY (Don’t Repeat Yourself) coding method reduces unnecessary code, improving email load times and the user experience. Gmail clips the content of the email after 100KB.
• Images and GIFs that have larger file sizes have a dramatic effect on loading speed.
• Implementing Dark Mode modifications can improve the experience for the growing number of Dark Mode users.
• Accessibility plays a crucial role in engagement. By using high-contrast text, image alt text, and semantic HTML, you can improve readability for users with visual impairments. To improve the accessibility of your email content, cross-reference to make sure you’re meeting WCAG 2A & 2AA requirements, and follow best practices such as short subject lines, large buttons, left-aligned text, and limited uppercase usage.
  

Tuning up your deliverability is an extremely cost-effective way to supercharge the ROI from your CRM acquisition campaigns – in other words, you’ll drive a huge increase in the average value of each user in your database. Reach out and start a conversation if you need a guiding hand in improving this all-important email KPI.

Glossary

Delivery determines if an email was received by our subscribers’ servers of the provided inbox. Emails are considered delivered if they do not bounce.

Deliverability determines where your email lands once it has been delivered successfully. Your email could end up in the spam folder or a promotional category.

Sender Reputation is how inbox providers see your brand, and it is influenced by spam complaints, bounce rates, and engagement.

CAN-SPAM Act (Controlling the Assault of Non-Solicited Pornography and Marketing Act) is a law enforced by the FTC that sets the rules for commercial email, establishes requirements for commercial messages, gives recipients the right to have you stop emailing them, and spells out penalties for violations.

DMARC (Domain-Based Message Authentication, Reporting and Conformance) is an email authentication protocol that helps protect domains from unauthorized use, particularly domain spoofing and phishing attacks, by verifying the authenticity of emails claiming to be from a specific domain.

DKIM (DomainKeys Identified Mail) is an email authentication protocol that uses digital signatures to verify that an email was sent by the claimed sender and hasn’t been altered in transit.

SPF (Sender Policy Framework) is an authentication protocol that lists IP addresses in a record that is authorized to send an email on behalf of domains.

BIMI (Brand Indicators for Message Identification) is an emerging email specification that enables the use of brand-controlled logos within supporting email clients.