How do I troubleshoot delivery errors and TempFail messages in Klaviyo when using Gmail?

Key findings

• TempFail indication: Gmail's TempFail messages often suggest a temporary issue rather than a permanent rejection. These can be due to various factors, including low sender reputation or recipient mailbox issues.
• DMARC status: Even with a strong DMARC p=quarantine policy and high authentication rates, TempFails can occur. This indicates that the issue might not be directly related to authentication alignment, as a p=quarantine policy generally defers rather than rejects.
• Log analysis is key: The most effective way to pinpoint the exact cause of delivery errors is to examine detailed delivery logs provided by your email service provider (ESP) or mail server. Look for specific error codes and messages from Gmail (e.g., gsmtp errors).
• Content vs. connection issues: The stage at which an email is rejected in the SMTP transaction (before or after DATA) can reveal whether the problem is related to sender reputation, IP address, or specific content within the email.

Key considerations

• Shared IP challenges: When using a shared IP (as common with ESPs like Klaviyo), direct access to detailed server logs for grep commands may not be available. In such cases, contacting Klaviyo support for bounce reports and insights is essential.
• Klaviyo bounce data: Focus on the bounce reasons within Klaviyo's interface, especially for Gmail addresses. This meta data often contains the specific rejection reason, helping to diagnose if it's content, link, or recipient-related. More information can be found on Klaviyo's help center on email deliverability.
• Google Postmaster Tools: Google Postmaster Tools (GPT) provides valuable insights into deliverability, domain reputation, and spam rates. However, it may not detail specific reasons for individual TempFails, particularly if the email wasn't delivered to begin with. You can use it to troubleshoot and improve low Gmail email deliverability rates.
• Content and links: Examine email content for potentially problematic elements, such as suspicious links or heavily spammed phrases, as these can trigger Gmail's filters to temporarily block messages due to suspected spam.

Key opinions

• Klaviyo bounce data is primary: Many marketers suggest starting the troubleshooting process directly within Klaviyo by checking the bounce reasons for Gmail addresses, as this meta data often contains the specific details needed.
• Shared IP limitations: Marketers on shared IP addresses acknowledge that they usually do not have direct access to server-side logs (e.g., for grep commands) and must rely on their ESP's reporting or support for deeper insights. This is a common issue for those wondering why their Klaviyo shared IP has Gmail deliverability issues.
• DMARC is usually not the culprit for TempFails: While DMARC is crucial for email authentication, marketers often find that TempFail messages, especially with a p=quarantine policy, are unlikely to be directly caused by DMARC failures alone.
• Check other mailstreams: If Klaviyo seems to be performing well (high open rates, low spam complaints), marketers suggest looking at other platforms or services that send email on behalf of the domain (e.g., transactional email providers, CRM systems) as potential sources of the problem.

Key considerations

• Distinguish TempFail from spam complaints: It's important to differentiate between temporary delivery errors and actual spam complaints. Spam rates reflect emails that were delivered but marked as spam by recipients, whereas TempFails indicate non-delivery (even if temporary). Understanding this distinction helps in troubleshooting sudden Gmail spam delivery.
• Impact of specific links: Problematic links, especially those associated with flagged tracking tools, can lead to delivery issues. Marketers suggest reviewing all links in emails and testing their impact. You can read more about fixing Gmail deliverability issues.
• Mailbox full bounces: Temporary mailbox full bounces are a common type of TempFail. While validation tools might filter some, Gmail's temporary nature means recipients might clear space later, allowing delivery. These types of temporary errors relate to Gmail soft bounce errors.

Key opinions

• SMTP transaction analysis: Experts recommend examining where in the SMTP conversation a rejection occurs. If it's before the DATA command, it points to IP or domain reputation. If after, content or specific links are more likely the cause. This process is key to diagnosing and resolving email deliverability issues.
• Temporary nature of Gmail failures: Gmail's mailbox full responses are often temporary. Recipients might clear space, leading to eventual delivery. This is a common soft bounce error and does not necessarily indicate a permanent block. This can sometimes cause slow email delivery to Gmail.
• Low reputation deferrals: TempFail messages can be indicative of low sender or domain reputation. Gmail may issue temporary rejections with specific error codes (e.g., 421 4.7.0) signaling suspicious activity or poor sending practices. For more information, you can visit Gmail's official support page on sender guidelines.

Key considerations

• Log parsing tools: While shared IPs limit direct access, knowing that tools like grep are used for log analysis can help in requesting specific data from ESP support or understanding log formats. This is a common approach for experts troubleshooting customer deliverability issues.
• Authentication impact: Although DMARC might not directly cause TempFails with a quarantine policy, maintaining proper SPF and DKIM authentication is foundational for good sender reputation, which directly influences deliverability and reduces temporary rejections. Learn more about DMARC, SPF, and DKIM authentication.
• Segment or content specific issues: If a small fraction of mail is being affected, it's highly improbable that the entire ESP's service (Klaviyo) is at fault. Experts suggest that a particular segment, email content, or embedded links might be triggering Gmail's filtering mechanisms.

Key findings

• Domain alignment is critical: Klaviyo's documentation emphasizes that confirming domain alignment, where your sender email's root domain matches the authentication domain, is crucial for strong deliverability and avoiding spam filters.
• Bounces are rejections: Documentation defines a bounce as an email that is either not successfully delivered or is rejected by a recipient's inbox provider. Understanding bounce types (hard vs. soft) is key to managing your lists and reputation.
• Google's bulk sender guidelines: Google's documentation provides specific guidelines for bulk senders regarding authentication (SPF, DKIM, DMARC), spam rates, and clean lists. Non-compliance can lead to delivery delays or rejections (TempFails included). You can read about why emails to Gmail experience delivery delays.

Key considerations

• Interpreting error codes: Documentation often includes lists of SMTP error codes and their meanings. Familiarizing yourself with these codes (e.g., 4xx for temporary failures, 5xx for permanent failures) is vital for accurate troubleshooting. This can help troubleshoot intermittent email delivery failures.
• Sender reputation factors: Documentation from major ISPs (like Google) frequently details factors influencing sender reputation, such as spam complaint rates, email volume, and content quality. Maintaining a strong reputation is key to avoiding blocklists and temporary rejections.
• Engagement metrics: Documentation from ESPs (such as Klaviyo) often stresses the importance of monitoring engagement metrics like open rates and click-through rates. Consistent high engagement signals good list health and relevant content, positively impacting deliverability and reducing the likelihood of TempFails.