What are the key areas to cover in deliverability training for email marketers?
Michael Ko
Co-founder & CEO, Suped
Published 10 Jul 2025
Updated 17 Aug 2025
7 min read
The world of email deliverability is constantly evolving, with recent changes from major providers like Google and Yahoo emphasizing the critical need for marketers to understand its nuances. It's no longer enough to simply send emails and hope they land in the inbox. Marketers must grasp the technical foundations and best practices to ensure their campaigns reach their intended audience, avoid spam folders, and maintain a healthy sender reputation.
Effective deliverability training equips email marketers with the knowledge to navigate this complex landscape. Without it, even the most compelling email content risks being unseen, leading to wasted effort and missed opportunities. Understanding the core principles of how emails are delivered, filtered, and perceived by mailbox providers is fundamental to successful email marketing in 2024 and beyond.
For marketers, training should cover both the 'why' behind deliverability issues and the 'how' of implementing solutions. It should provide practical, actionable insights that can be immediately applied to improve campaign performance and foster stronger customer relationships through consistent inbox placement. Neglecting deliverability can lead to significant revenue loss and damage to brand reputation.
Email authentication and sender reputation
One of the most crucial areas for any email marketer's deliverability training is email authentication and sender reputation. These are the bedrock upon which all successful email programs are built. Without proper authentication, emails are highly likely to be flagged as spam, regardless of their content or list quality.
Training should demystify key protocols like SPF, DKIM, and DMARC. Marketers need to understand what each record does, how they work together to verify sender identity, and their impact on email deliverability. This includes practical guidance on setting up and maintaining these DNS records correctly, as well as interpreting DMARC reports to identify and resolve authentication issues quickly.
Furthermore, sender reputation is like a credit score for your email-sending domain and IP address. Training must cover the factors that build or degrade reputation, such as bounce rates, spam complaints, and engagement metrics. Marketers need to learn how to monitor their reputation, understand common pitfalls that can damage it, and implement strategies for improving sender reputation over time. This includes proactive steps like warming up new IPs and domains, and reactive measures for recovering from a poor reputation or a blocklist listing (also known as blacklisting).
Understanding DMARC policies
DMARC policies dictate how receiving mail servers should handle emails that fail authentication. Marketers should understand the progression from a relaxed `p=none` policy (monitor only) to more stringent `p=quarantine` (send to spam) and `p=reject` (block delivery) policies.
Effective list hygiene is paramount to good deliverability. Training should emphasize that a clean, engaged email list is one of the most powerful assets a marketer can have. This includes understanding the importance of opt-in practices, particularly double opt-in, to ensure all subscribers have explicitly consented to receive emails.
Marketers need to learn how to identify and remove inactive or invalid email addresses regularly. This prevents high bounce rates, which negatively impact sender reputation. Understanding different types of bounces (hard vs. soft) and how to manage them is also essential. A key component of this training should be on identifying and avoiding spam traps, which are email addresses specifically designed to catch spammers.
Beyond list cleaning, training should cover strategies for maximizing subscriber engagement. This involves understanding what content resonates with subscribers, segmenting lists for targeted messaging, and encouraging positive interactions like opens, clicks, and replies. Low engagement signals can tell mailbox providers that your content isn't valuable, potentially leading to lower inbox placement or even a blocklist (or blacklist) listing for your sending IP or domain.
Good list practices
Permission-based lists: Always use double opt-in to ensure subscribers genuinely want your emails.
Regular cleaning: Remove unengaged subscribers and bounced addresses promptly. Regularly run a free email tester to validate addresses.
Segmentation: Target specific groups with relevant content to boost engagement.
Bad list practices (avoid!)
Purchased lists: These often contain spam traps and lead to high complaint rates.
Ignoring bounces: Failing to remove hard bounces will damage your sender reputation.
Infrequent sending: Long gaps can lead to subscribers forgetting they opted in, increasing spam complaints.
Content and campaign best practices
The content of your emails plays a significant role in deliverability. Training for marketers should highlight how email content, design, and sending practices influence whether an email lands in the inbox or the spam folder. This means understanding common spam triggers in subject lines, body text, and links.
Best practices for email design and HTML coding are also critical. Overly complex HTML, broken images, or an imbalanced text-to-image ratio can raise red flags with spam filters. Marketers should learn about responsive design to ensure emails display correctly across various devices and email clients, contributing to a positive user experience and better engagement.
Additionally, the training should cover the strategic use of personalization, relevant calls-to-action, and A/B testing to optimize content for engagement and deliverability. It's not just about avoiding negatives; it's about actively creating emails that recipients want to open and interact with. Understanding how new requirements from providers like Gmail impact content and sending frequency is also vital.
Content elements and their impact
The elements within your email can significantly affect its deliverability. Knowing what to include and what to avoid is crucial.
Subject lines: Avoid excessive capitalization, exclamation points, or spammy keywords.
Images vs. text: Maintain a good balance. Image-only emails are often flagged as spam.
Links: Ensure all links are reputable and don't redirect through suspicious domains. Shortened links should be used with caution.
Personalization: Use it wisely. Generic or irrelevant personalization can backfire.
Monitoring and troubleshooting deliverability
Even with the best practices in place, deliverability issues can arise. Therefore, training should equip marketers with the skills to monitor and troubleshoot problems effectively. This includes understanding the various tools available for deliverability monitoring and how to interpret the data they provide.
Key metrics to monitor include open rates, click-through rates, bounce rates, and spam complaint rates. Marketers should be familiar with Google Postmaster Tools and other postmaster pages (e.g., Outlook) to gain insights into their sender reputation and email performance with major ISPs. Understanding how to use a blocklist checker is also important.
Finally, training should include strategies for recovery when deliverability issues occur. This might involve appealing blocklist (or blacklist) listings, segmenting problematic email sends, or re-engaging inactive subscribers. The goal is to equip marketers with a proactive mindset, enabling them to identify potential problems before they escalate and to effectively implement solutions when challenges arise. This knowledge ensures continuity and effectiveness in their email marketing efforts.
Metric
What it tells you
Actionable insights
Bounce rate
Percentage of emails that couldn't be delivered.
High rates indicate poor list hygiene or content issues. Clean your list.
Complaint rate
Percentage of recipients marking your email as spam.
Too many complaints damage reputation. Review content, frequency, and consent.
Open rate
Percentage of recipients opening your email.
Low open rates indicate poor subject lines or low sender reputation.
Click-through rate (CTR)
Percentage of recipients clicking a link in your email.
Continuously educate yourself and your team on evolving sender requirements and industry best practices.
Implement a structured email onboarding process that includes proper IP warming and content testing.
Prioritize email list hygiene by regularly removing unengaged subscribers and invalid addresses.
Common pitfalls
Sending emails to purchased or old, unverified lists without proper re-engagement strategies.
Ignoring DMARC reports or failing to act on authentication failures and bounce notifications.
Over-relying on promotional content without balancing with valuable, engaging information.
Expert tips
Develop a deep understanding of how each ISP (like Gmail or Yahoo) evaluates incoming email traffic.
Proactively monitor your sender reputation and DNS records to catch potential issues early.
Regularly review engagement metrics and adjust your sending strategy based on subscriber behavior.
Marketer view
Marketer from Email Geeks says they answered the survey from the perspective of what they think others need in terms of deliverability training.
2024-02-05 - Email Geeks
Marketer view
Marketer from Email Geeks says that as more people take on deliverability responsibilities, training options are increasingly important, and they are excited about new partnerships in the training certification space.
2024-02-05 - Email Geeks
Empowering marketers for inbox success
Investing in comprehensive deliverability training for email marketers is no longer an option, but a necessity. The landscape of email security and inbox placement is complex and ever-changing, requiring marketers to be agile and well-informed.
By focusing on email authentication, sender reputation, list hygiene, engagement, content best practices, and effective monitoring, marketers can significantly improve their email campaign performance. This training empowers them to not only avoid common pitfalls, but also to proactively optimize their sending strategy for maximum impact.
Ultimately, robust deliverability training transforms email marketing from a hopeful endeavor into a strategic, measurable, and highly effective channel for engaging customers and driving business growth.
Gmail impact content and sending frequency is also vital.
Outlook) to gain insights into their sender reputation and email performance with major ISPs. Understanding how to use a blocklist checker is also important.
