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What you’ll learn:
Email deliverability is essential for ensuring messages reach subscribers’ inboxes and maintaining trust in brand communications.
Maintaining deliverability requires a proactive, ongoing strategy grounded in best practices like authentication, list hygiene, and performance monitoring.
As internet service providers evolve their privacy standards, marketers must adapt by implementing required protocols like DMARC and one-click unsubscribe to stay compliant and effective.
What Is Deliverability and Why Is It Important?
Email is one of the most powerful tools in a marketer’s arsenal. Timeless and effective, it bridges the gap between customers and marketers while enabling communication across customer experience touchpoints. Whether you’re an email marketer or a customer, common challenges persist in ensuring emails successfully reach a subscriber’s inbox and trusting the communication is authentic and genuinely sent from the claimed company. At the heart of both concerns lies a critical shared foundation—email deliverability. We must understand the basics of email deliverability to achieve successful inbox delivery and build customer trust.
Deliverability refers to an email’s ability to reach a subscriber’s inbox. No matter how personalized, curated, or optimized an email message is, the campaign’s effectiveness reduces dramatically if it fails to land in the recipient’s inbox. Marketers invest substantial time, resources, and effort into crafting emails, making it crucial to optimize deliverability to maximize engagement. Deliverability is not simply a box to check but an evergreen strategy woven throughout the email channel.
A solid understanding of email deliverability empowers email marketers to make informed decisions about optimizing their campaign’s ROI. Email marketers must be proactive since deliverability is an ongoing process and can vary significantly from month to month.
Key Elements to Maintain Healthy Deliverability
There are many elements to consider when establishing and maintaining a quality relationship between email deliverability and your target audience. At a high level, foundational best practices include:
IP warming: gradually sending emails over a period of time for new or stale domains to establish a positive sender reputation
Easy opt-in and opt-out processes: allowing subscribers to easily communicate when they want to hear from you while honoring their privacy
List throttling: sending emails out in batches to avoid spam triggers and blocks by internet service providers (e.g., Google, Yahoo, etc.)
List hygiene practice: routinely ensuring the audience is engaged and interacting with your content
Sending engaging and relevant content: meeting subscribers where they are throughout their experience with high-value, timely, and relevant content.
Implementation of SPF, DKIM, and DMARC authentication: these security measures help prevent spoofing and phishing attempts using your domains and help ISPs verify email legitimacy
Monitoring of reputation and blocklists: ensuring that your IP and domain aren’t flagged and taking immediate action to mitigate and solve any delivery issues
AI-powered email analytics: tools to help predict optimal send times, segment audiences based on behavior, and identify patterns in engagement
Although applying best practices before and during the sends is significant, it is also mandatory for email marketers to consider best practices post-deployment. You must monitor and evaluate the performance of a campaign’s engagements to ensure there are no flags, such as spikes in hard bounces or block bounces, that could impact the health of the sender domain and deliverability. You will need to hyperfocus on the frequency and saturation of their campaigns. Ensuring the emails’ content, frequency, and cadence are aligned with the recipient’s expectations is important to avoid message fatigue. Most importantly, if flags such as a high bounce rate are observed, you must take action to mitigate and optimize deliverability.
The New State of Email Marketing
As the digital marketing landscape and individual privacy continue to transform, internet service providers (ISPs) are updating their requirements. Our team recently documented how Apple iOS 18 has changed the email landscape and now Microsoft, Yahoo!, and Google have announced changes, many of which have shifted common deliverability best practices into requirements. These changes increase a recipient’s confidence in the email channel to build trust about who it is from and penalize spammers. Here’s what you need to know:
Microsoft High-Volume Senders Require Authentication To enhance email security, quality, and trust, Microsoft now requires high-volume senders to implement SPF, DKIM, and DMAC protocols. A high-volume sender is defined as organizations that send more than 5,000 emails per day to Microsoft domains, such as hotmail.com, outlook.com, msn.com, and live.com. While this requirement pertains to high-volume senders, adopting these authentication practices is a smart move for all to ensure better deliverability and brand protection.
DMARC Is Mandatory Yahoo! and Google have emphasized the importance of senders authenticating their emails, but now DMARC is a requirement. For Microsoft, this is a requirement for high-volume senders. Now, more than ever, is an opportune time to verify that your SPF, DKIM, and DMARC records are properly set up. These authentication records assure ISPs of your legitimacy. These adjustments align with well-established industry best practices, which Klick already considers integral to its approach.
One-Click Unsubscribe Microsoft, Yahoo!, and Google are seeking bulk senders or email marketers to simplify the unsubscribe process for recipients. Ensure emails offer a one-click unsubscribe option in the header and honor user requests within two days. At Klick, our deployment partners take care of this automatically, offering a list-unsubscribe feature. Now is also a good time to review your opt-in and opt-out processes, ensuring they are clear and efficient for users.
Maintain Spam Rates Below 0.3% Although deliverability metrics can fluctuate, Yahoo! and Google expect senders to maintain spam complaint rates below 0.3% or preferably under 0.1%. Monitor your spam rates closely, adhering to best practices like delivering valuable content to the right subscriber at the right time for optimal results. It’s a good idea to monitor your monthly spam rate using tools such as aboutmy.email and Google Postmaster. Additionally, it’s a good idea to proactively monitor your domains by monitoring weekly metrics from account send summary, bounce, and spam-rate reports.
Klick’s Approach to Deliverability
From content design to campaign deployment and monitoring, the Klick Customer Engagement Platforms (CEP) Team applies best practices to set client domains up for success regarding deliverability. Starting from email development and configuration, we prioritize and implement key features such as easy opt-out practices, domain authentication, link tracking, view-in-browser links, personalization, and A/B testing for a seamless user experience. We also capture data to evaluate and analyze to shape future campaigns efficiently.
Engaging content is balanced with data protection to enhance the recipient experience while prioritizing compliance. Today, using relevant and personalized content is not enough. With partners like Everest Validity, we review all emails against design, content, and spam standards to ensure they are a quality asset regardless of the device and ISP used. Along with the content, a recipient’s personal identifiable information (PII) is encrypted to ensure this information is secured. For example, an unsubscribe link may contain an email address where encryption ensures that this information is not shared publicly without compromising the customer experience.
During the deployment, we apply best practices such as audience-list validation and send throttling. These practices support a target audience while prioritizing the sender’s IP, domain reputation, and email deliverability. Evergreen practices continue after deployment, with post-launch monitoring exercises to track deliverability and engagement rates to analyze and optimize results for future deployments.
Concluding Thoughts
Even the “perfect email” won’t convert if it’s not delivered. Email marketers must stay proactive, adapting to the latest deliverability requirements and best practices. By consistently monitoring and prioritizing authentication, engagement, and list hygiene, brands can ensure their emails are delivered and recognized as high-quality, relevant content—exactly what subscribers expect and value.
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References
Acoustic, 2025 Marketing Benchmark Report [Report]. Acoustic. https://www.acoustic.com/reports/marketing-benchmark-report
Brummer, C., Email authentication best practices for 2025. Standard Beagle. https://standardbeagle.com/email-authentication-best-practices-for-2025/
Admin, Top 10 AI Tools for Email Marketing in 2025 to Maximize Your Campaign Success. Techlopedia. https://techlopedia.com/ai/ai-tools-for-email-marketing/
New Year, New Email Deliverability Rules: Improve Your Email Sender Score [Webinar]. Salesforce, January 18, 2024.
Essential strategies to survive the NEW Yahoo! and Google (Yahoogle!) technical requirements [Webinar]. Nine Lives Digital, January 9, 2024.
著者
Daeyoung Kang
Associate Director, Customer Engagement Platforms
Daeyoung Kang is a detail-oriented and strategic campaign operations lead focused on delivering high-quality marketing automation solutions. He manages cross-functional and offshore teams to ensure seamless integration and execution for clients. Known for his proactive mindset, Daeyoung advocates for process improvements, operational efficiency, and strong collaboration across teams. With growing expertise in customer engagement platform (CEP) solutions, he is adept at maintaining delivery standards and identifying opportunities to improve how teams work and deliver.
Claire Howard
Campaign Manager, Customer Engagement Platforms
Claire is a strategic campaign manager with over eight years of experience delivering high-impact omnichannel campaigns across healthcare, advertising, endurance, and consumer goods. At Klick, she leads marketing automation initiatives from strategy through execution, specializing in data-driven personalization and Salesforce Marketing Cloud for enterprise life sciences clients. With expertise in technical platforms and business outcomes, Claire is a trusted partner in driving performance and efficiency through scalable solutions supporting long-term client success.
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