How can I diagnose and resolve email deliverability issues when emails aren't reaching intended recipients?

Key findings

• Spam rate threshold: A user-reported spam rate exceeding 0.1% (e.g., 0.5% to 1.5%) is considered high and can significantly impact email deliverability, even if general IP and domain reputation appear high in tools like Google Postmaster Tools.
• Cold email impact: Sending cold emails, particularly from the same domain used for corporate or transactional communications, can lead to filtering and emails landing in spam folders. This practice often contradicts best practices for maintaining a strong sender reputation.
• Authentication metrics: High authenticated traffic rates (near 100% for DKIM and SPF) indicate proper setup of email authentication protocols, which is a foundational element for deliverability but doesn't guarantee inbox placement if other factors (like spam complaints) are problematic. Learn more about DMARC, SPF, and DKIM.
• Diagnostic limitations: Google Postmaster Tools primarily provides data for emails sent to @gmail.com addresses, not for emails delivered to Google Workspace accounts. This limitation means the data might not reflect the full scope of deliverability issues across all recipient domains.

Key considerations

• Address spam complaints: High spam complaint rates are a critical indicator of poor list quality or content relevance. Actively work to reduce these rates by improving list hygiene, ensuring opt-in consent, and providing valuable content. This is a primary factor in improving sender reputation.
• Separate cold email infrastructure: If cold email is a necessary part of your strategy, consider setting up a completely separate email infrastructure, including a distinct domain, to isolate its potential negative impact from your primary corporate email domain.
• Verify delivery status: When emails aren't reaching recipients, confirm whether they are going to spam folders or are completely blocked. This distinction is vital for accurate diagnosis and troubleshooting. For more information, read this ActiveCampaign article.
• Monitor beyond basic metrics: While high IP/domain reputation is good, delve into specific metrics like spam complaint rates and feedback loops to identify subtle signs of deliverability issues. This holistic approach helps in diagnosing complex problems.

Key opinions

• New domain challenges: Newer domains (e.g., 4 months old) often face deliverability hurdles, particularly when sending via common platforms like Google Workspace or HubSpot, due to a lack of established sending history and reputation.
• DKIM importance: Ensuring DKIM is enabled and correctly configured is a fundamental step, as Google, by default, signs emails with its own keys, which can affect authentication if not properly managed.
• Cold email reputation risk: Sending cold emails is commonly cited as a major factor impacting sender reputation and overall deliverability, potentially leading to increased spam complaints and inbox placement issues. This is a common theme when emails go to spam.
• Tools for reputation analysis: Marketers frequently seek tools to analyze sender reputation and identify specific issues, with Google Postmaster Tools being a common free option, though its data scope is a key consideration. For a deep dive, see our ultimate guide to Google Postmaster Tools.
• Importance of engagement: Opted-in and engaged recipients are crucial for maintaining high deliverability rates, as opposed to cold outreach, which inherently carries higher risks of deliverability and placement issues.

Key considerations

• Monitor spam rates diligently: While IP and domain reputation might look good, a consistently high spam complaint rate (e.g., above 0.1%) indicates a significant problem that needs immediate attention to avoid further deliverability declines. This directly impacts your deliverability rate.
• Confirm email destination: When emails aren't arriving, verify with recipients if messages are going to spam folders or are not received at all, as this distinction guides the troubleshooting process.
• Review content and attachments: Even if previous emails were delivered, subsequent emails with attachments or different content might be flagged. Reviewing content for spam triggers is crucial, especially when intermittent failures occur. For more insights, check this Twilio article on email delivery failures.
• Strategic domain use: Avoid mixing cold email campaigns with primary corporate communications on the same domain, as this can easily compromise the reputation of your main domain.

Key opinions

• Spam complaint sensitivity: The accepted risk threshold for spam complaints is extremely low, approximately 0.1%. Any rates above this, even seemingly small, are considered high and indicative of significant problems that lead to emails being filtered.
• Cold email isolation: If an organization insists on sending cold emails, experts strongly advise setting up a completely separate email infrastructure, including a different domain, to prevent its negative reputation from affecting the primary corporate domain's deliverability.
• Google Postmaster Tools scope: It's crucial to understand that Google Postmaster Tools provides spam rate and reputation data exclusively for mail sent directly to @gmail.com addresses, not for mail delivered to Google Workspace accounts. This limits its comprehensive diagnostic value for business-to-business (B2B) sending. More on Google Postmaster Tools domain reputation.
• Recipient end filtering: If emails are being blocked entirely (not even reaching the spam folder), this could indicate significant issues on the recipient's end due to aggressive filtering or specific blocklists, necessitating direct confirmation with the recipient.

Key considerations

• Prioritize opted-in engagement: Focusing on sending emails to opted-in and engaged recipients is paramount for high deliverability and avoiding spam classification. This builds a positive sender reputation over time.
• Distinguish spam from blocks: It is critical to ascertain whether undelivered emails are landing in spam folders or being completely blocked. The former points to content/reputation issues, while the latter suggests more severe filtering or blacklist presence.
• Proactive reputation management: Even with seemingly good reputation metrics, a high spam complaint rate can be a ticking time bomb. Proactively addressing the root causes of complaints is essential for sustained deliverability. This links to recovering domain reputation.
• Infrastructure separation: For specific high-risk sending types, like cold outreach, consider dedicating separate IP addresses, domains, and sending platforms to insulate your main sending infrastructure from potential damage.

Key findings

• Authentication requirements: Documentation consistently highlights the necessity of SPF, DKIM, and DMARC for email authentication, which verifies sender identity and reduces the likelihood of emails being marked as spam or rejected. For more, see our list of DMARC tags.
• Spam complaint rates: Many help articles and guidelines specify that a spam complaint rate of around 0.1% is a critical threshold. Exceeding this can lead to severe deliverability issues and reputation damage.
• Feedback loops (FBLs): Documentation explains FBLs as mechanisms that inform senders when recipients mark their emails as spam, allowing senders to remove non-engaged users from their lists and mitigate future complaints.
• Reputation monitoring tools: Official resources, such as Google's Postmaster Tools FAQ, outline how to use their platforms to monitor sender reputation, spam rates, and other vital deliverability metrics, though with specific limitations on data coverage.

Key considerations

• Implement DMARC correctly: Ensure your DMARC record is properly configured and aligned with SPF and DKIM. Incorrect setup can lead to verification failures, impacting deliverability. Get help with common DMARC issues.
• Adhere to best practices for new domains: When using a new domain, documentation advises a cautious warming-up approach, starting with low volumes of highly engaged recipients to build a positive reputation before scaling up sending volume.
• Leverage feedback loop data: Actively use data from FBLs to clean your email lists of recipients who mark your emails as spam. This proactive measure prevents further complaints and improves overall deliverability.
• Understand tool limitations: Be aware that tools like Google Postmaster Tools provide specific insights (e.g., only for @gmail.com). Complement these with other monitoring methods to get a comprehensive view of your deliverability across all recipients. For more information, see the Postmaster Tools FAQs.