What should I include in an email deliverability checklist?
Matthew Whittaker
Co-founder & CTO, Suped
Published 15 Jun 2025
Updated 16 Aug 2025
8 min read
Achieving strong email deliverability is crucial for any successful email campaign. It ensures your messages reach the inbox, not the spam folder. To consistently hit your recipients' inboxes, you need a comprehensive approach that covers technical setup, sender reputation, list management, and content quality. Without a structured checklist, it's easy to overlook critical components that can significantly impact your email performance.
I've seen many businesses struggle with deliverability simply because they lack a systematic way to manage all the moving parts. A robust email deliverability checklist provides a clear roadmap, guiding you through the essential steps needed to optimize your email program and maintain a healthy sending reputation. It’s about proactive management rather than reactive troubleshooting.
Technical foundations
The foundation of good email deliverability lies in correctly configured technical protocols. These protocols act as trust signals, verifying to recipient mail servers that your emails are legitimate and haven't been tampered with. Ignoring these can lead to messages being flagged as suspicious or outright rejected, regardless of your content or list quality.
Core authentication protocols
First, ensure your SPF, DKIM, and DMARC records are properly set up. Sender Policy Framework (SPF) specifies which mail servers are authorized to send email on behalf of your domain. DomainKeys Identified Mail (DKIM) adds a digital signature to your emails, allowing recipients to verify that the email was sent by the domain owner and wasn't altered in transit. Domain-based Message Authentication, Reporting, and Conformance (DMARC) builds on SPF and DKIM, giving you control over what happens to emails that fail these checks and providing valuable reporting on your email authentication status.
Beyond these, consider implementing Brand Indicators for Message Identification (BIMI) if brand recognition is a priority. BIMI allows your brand's logo to appear next to your emails in supporting inboxes, further enhancing trust and visibility. While not directly a deliverability factor, it signals to recipients that you are a legitimate sender.
Make sure your mail servers are properly configured to handle replies. If recipients reply to your emails, ensure those replies are routed to an active mailbox that is regularly monitored. An unmonitored reply-to address can signal to mailbox providers that you are not engaging with your audience, which can negatively impact your sender reputation over time.
Sender reputation
Your sender reputation is paramount. Mailbox providers assess your reputation based on various factors, including bounce rates, spam complaints, and engagement metrics. A poor reputation means your emails are more likely to land in the spam folder or be rejected entirely. Regularly monitoring and maintaining your reputation is key to consistent inbox placement.
Monitoring and maintenance
Actively monitor your IP and domain reputation. Tools like Google Postmaster Tools offer insights into your sending performance to Gmail and other recipients. Be vigilant about email blocklists (or blacklists), as being listed can severely damage your deliverability. Regularly check if your sending IPs or domains are on any major public blocklists. If you find yourself on a blacklist, take immediate action to address the underlying cause and request delisting.
Sender reputation audit
A comprehensive audit should be a regular part of your routine. This includes assessing your sending patterns, reviewing bounce and complaint rates, and checking feedback loop registrations. For newly acquired or warmed-up domains, a careful domain warm-up process is critical to build trust with mailbox providers before sending large volumes of mail.
Maintaining a healthy sending volume is also important. Avoid sending huge spikes of email after periods of inactivity, as this can look suspicious to mailbox providers. Consistent sending habits at a reasonable tempo help maintain a stable reputation. If you're sending cold emails, consider using dedicated domains for cold outreach to protect your primary domain's reputation.
List hygiene and engagement
Even with perfect technical setup and a pristine reputation, a poor email list will tank your deliverability. Your list is the bedrock of your email program, and its quality directly influences how mailbox providers view your sending practices. A clean, engaged list signals that your content is valued by recipients, whereas a neglected list can lead to high bounces and spam complaints.
List hygiene best practices
Implement a double opt-in process for all new subscribers to ensure they genuinely want to receive your emails. This significantly reduces the chances of bounces and spam complaints. Regularly clean your email list by removing inactive subscribers, hard bounces, and known spam traps. Sending to unengaged or invalid addresses signals poor list management, which hurts your sender reputation.
Engagement is a two-way street. Mailbox providers track how recipients interact with your emails. High open, click, and reply rates positively impact your deliverability, while low engagement, deletions without opening, and marking as spam can harm it. Segment your audience based on engagement levels, sending more frequently to your most active subscribers and less to those who rarely open your emails.
Engagement strategies
Relevant content: Ensure your content is tailored to your audience's interests and expectations. Personalization can significantly boost engagement.
Clear CTAs: Include compelling calls to action that encourage interaction and make it clear what you want recipients to do.
Feedback loops: Register for feedback loops with major ISPs. This notifies you when someone marks your email as spam, allowing you to remove them from your list immediately and prevent further damage to your reputation. A high complaint rate is a serious red flag.
Content and compliance
The content of your emails plays a direct role in deliverability. Even if your technical setup is perfect, spammy content or deceptive practices will land your emails in the junk folder. Your content needs to be clean, relevant, and provide value to the recipient. This helps avoid spam filters and encourages positive engagement.
Content optimization
Craft clear, concise, and relevant subject lines and email copy. Avoid excessive capitalization, exclamation points, and spam-trigger words. Always include an easy-to-find and functioning unsubscribe link in every email. Offering a clear path to opt-out is not just legally required in many regions but also prevents recipients from marking your emails as spam, which is far more damaging to your reputation. Provide both HTML and plain text versions of your emails to ensure readability across all email clients.
Internal processes and compliance
Beyond the technical and content aspects, internal processes and compliance are critical yet often overlooked. Ensure you have clear processes for email address acquisition, unsubscribe requests, and data management. Designate someone responsible for email across your entire organization to prevent accidental misconfigurations that can damage your deliverability.
Properly managing Personally Identifiable Information (PII) is also essential for compliance and deliverability. Misuse or mishandling of email addresses, such as selling them to third parties or repurposing them without consent, can lead to severe blocklisting and legal repercussions. Having a dedicated person responsible for data privacy ensures these practices are avoided, protecting your brand's reputation and preventing deliverability issues linked to trust and privacy.
Views from the trenches
Best practices
Always maintain an audit trail for how your email addresses were acquired and ensure users are expecting your mail.
Regularly monitor your DMARC reports to identify and address any authentication failures or unauthorized sending.
Ensure your unsubscribe process is easy to find, functional, and compliant with all relevant laws and regulations.
Designate a specific individual or team internally responsible for all email-related matters across your organization.
Common pitfalls
Failing to monitor DNS records means changes by IT or vendors can accidentally break SPF or DKIM configurations.
Lack of internal responsibility for email can lead to unmonitored system alerts being blocked, causing critical failures.
Sending emails from rogue systems or unmanaged MTAs can lead to IP blocklisting and severe deliverability issues.
Misuse of Personally Identifiable Information (PII) like selling email lists damages sender reputation and leads to blocklisting.
Expert tips
Block port 25 egress for all systems except managed Mail Transfer Agents (MTAs) to prevent unauthorized sending.
Limit port 25 egress only to your chosen relay provider's IP addresses for tighter security and control.
Use plus tagging for unique email addresses to track exactly which source might be leaking your contact information.
Integrate compliance into your deliverability strategy because poor compliance often leads to poor deliverability.
Expert view
Expert from Email Geeks says that if no one is responsible for email across the organization, it's impossible to know if configurations like DMARC have changed or if new systems are sending mail incorrectly.
2023-05-02 - Email Geeks
Expert view
Expert from Email Geeks mentions that it's common for new IT hires or vendors to inadvertently break SPF or DKIM settings in DNS, highlighting the need for oversight.
2023-05-02 - Email Geeks
Maintaining inbox success
A comprehensive email deliverability checklist is an invaluable asset for any sender looking to achieve consistent inbox placement. By focusing on technical authentication, proactive reputation management, rigorous list hygiene, optimized content, and sound internal compliance processes, you can significantly improve your email deliverability rates. Regularly reviewing and updating your checklist will help you adapt to evolving email landscapes and maintain trust with both mailbox providers and your audience, ensuring your messages reach their intended destination time and again.
