Email deliverability remains one of the most important factors in B2B marketing success. Research from Return Path shows that more than one in five permission-based emails never make it to the inbox. For marketing operations teams, this translates into missed revenue, lower engagement, and wasted effort. Regular deliverability audits are therefore critical for protecting your sender reputation and keeping campaigns on track. This checklist outlines the key areas to review each month to ensure your emails consistently reach their intended recipients.
Understanding Email Deliverability Fundamentals
ISPs consider hundreds of signals when deciding whether to deliver your emails, filter them into spam, or block them outright. According to Validity’s 2023 Deliverability Benchmark Report, the average inbox placement rate across industries sits at 84.3%, which means almost one in six legitimate emails doesn’t land as intended. For marketing teams, this underlines the need for constant vigilance and routine auditing, rather than assuming that good content alone will carry messages to the inbox.
Sender Reputation Health Check
Your sender reputation functions like a credit score: it determines how much trust ISPs give to your campaigns. Complaint rates should stay under 0.1%, hard bounces below 2%, and soft bounces below 5%. Spam trap hits require immediate investigation since even a single one can signal poor practices. Blacklist status should also be checked regularly against major providers like Spamhaus, Barracuda, and SURBL. Free tools such as Sender Score offer high-level monitoring, while paid services provide detailed reporting that can help identify problems before they spiral.
Authentication Protocol Verification
Authentication protocols are essential for proving your legitimacy to ISPs. SPF records must be checked to ensure they include all authorised sending sources, yet research shows that more than a third of organisations have misconfigurations in this area. DKIM signatures should be verified to confirm alignment between public and private keys, while DMARC reports should be reviewed to catch authentication failures or suspicious activity. Companies with properly configured DMARC consistently see higher inbox placement rates, making this a non-negotiable part of every audit.
List Hygiene and Quality Assessment
Poor list quality is still the most common cause of deliverability issues. Each month, hard bounces should be removed immediately, unengaged subscribers should be suppressed after six to twelve months of inactivity, and addresses should be validated before use in campaigns. Role-based emails such as info@ or sales@ should also be avoided, as they are more likely to trigger spam filters. Clean lists improve deliverability, engagement, and ROI, and they also give marketing teams more reliable data for decision-making.
Content and Engagement Analysis
While spam filters still scan for content triggers, engagement signals are now one of the strongest deliverability factors. Content should be reviewed monthly to ensure spam trigger words are avoided, links are valid, and the text-to-image ratio is balanced at around 80/20. Emails must also be tested for mobile optimisation. On the engagement side, open rates, click-through rates, and time spent reading should all be monitored. Consistently low engagement tells ISPs that recipients don’t value your emails, which can hurt placement over time.
Technical Infrastructure Review
Your sending infrastructure should also be included in every monthly audit. Dedicated IP addresses provide more control but require ongoing maintenance and careful warming, while shared IPs carry the risk of being penalised for another sender’s poor behaviour. Monitor IP reputation scores, validate reverse DNS records, ensure TLS encryption is enabled, and check that your practices align with GDPR and CAN-SPAM requirements. Consistent sending patterns also build trust with ISPs, so review whether volumes are stable and predictable.
Deliverability Testing and Monitoring
Regular testing helps identify problems before they affect major campaigns. Test sends to Gmail, Outlook, and Yahoo should be part of every monthly audit, with placement monitored to ensure consistent inboxing. Tools such as GlockApps or Email on Acid provide detailed insights into how different providers are treating your emails, making it easier to spot and resolve issues early.
Taking Action on Audit Results
An audit is only valuable if it leads to corrective action. Any issues identified should be documented with a clear plan for resolution, prioritising high-impact problems like spam trap hits, blacklistings, or authentication failures. Improvements often take time to show up in deliverability metrics, so consistency and patience are essential. Reviewing and refining each month builds resilience and ensures gradual progress.
Maximising Your B2B Outreach Success
Strong deliverability is the foundation of successful email campaigns, but it doesn’t exist in isolation. At SendIQ, we combine best practices in email outreach with LinkedIn automation, cold calling, and website visitor identification, helping UK businesses deliver consistent engagement across multiple channels. With the right systems in place, your outreach can reach the right people, at the right time, and with the highest possible impact.
By running monthly deliverability audits and acting quickly on findings, your team can safeguard its sender reputation, keep emails landing in the inbox, and unlock the full revenue potential of your marketing efforts.
