How to get SMTP bounce logs from an ESP and what to do when emails go to spam?

Key findings

• Log access difficulty: ESPs often struggle to provide comprehensive SMTP bounce logs, especially for large date ranges, due to data volume and the involvement of third-party sending providers.
• Logs for spam issues: SMTP bounce logs primarily indicate delivery failures. They are generally not useful for diagnosing why emails land in spam folders, as these messages are usually initially accepted by the recipient server. For this, tools like Google Postmaster Tools or Microsoft SNDS are more effective.
• Spam causes: Inbox placement issues with major ISPs like Gmail are typically linked to sender domain reputation, content quality, and recipient engagement, rather than just the IP address or direct bounces.
• Prioritize engagement: For widespread deliverability problems, it is crucial to review your address collection process and focus on sending to recently opted-in and actively engaged contacts to improve sender reputation.

Key considerations

• Specificity of requests: When requesting logs from an ESP, be very specific about the data needed (e.g., small samples for particular recipients or specific timeframes) to increase your chances of success.
• Alternative diagnostics: For spam issues, prioritize investigating your email domain reputation, content quality, and list acquisition practices (e.g., checking for spam traps).
• Resting sends: Temporarily pausing email sends for a few days can sometimes help stabilize or improve a sender’s reputation, especially after a period of poor performance.
• ESP relationship: Maintain clear communication with your ESP’s support team, and escalate issues through official channels to receive appropriate assistance.

Key opinions

• Log data accessibility: Many marketers report that obtaining detailed SMTP log data from ESPs (like Klaviyo), especially for extended periods such as 30 days, is either impossible or takes a significant amount of time and effort.
• Ownership of data: Some ESPs may defer responsibility to their underlying sending provider (e.g., SendGrid) for log access, creating a bottleneck.
• Spam filtering distinction: Marketers emphasize that if emails are going to spam (not bouncing), raw SMTP logs are often unhelpful as they will typically show “gmail accepted this message for delivery”.
• High volume data challenges: Requests for large volumes of log data (e.g., a month's worth) are often rejected due to the immense complexity and time involved in separating and compiling usable client-specific information from shared platforms.

Key considerations

• Narrowing requests: To increase the chances of getting data, marketers are advised to make clearer and more restricted requests, focusing on specific email addresses or narrower timeframes.
• Address collection review: For widespread spam issues, marketers should start by scrutinizing their address collection processes, ensuring recent opt-ins and active recipient engagement.
• Domain vs. IP reputation: While shared IP pools can impact deliverability, marketers note that Gmail's spam filtering is predominantly influenced by domain reputation and content, not solely the IP address.
• Engaged contacts focus: When facing severe inboxing issues (like 0% inboxing at Gmail), prioritize sending only to the most engaged contacts to help rebuild sender reputation. This is a crucial step for recovering domain reputation.

Key opinions

• Log data effort: Experts (like U3HV54286 from Email Geeks) confirm that providing extensive log data, such as a month's worth, is a significant effort that could cost thousands of dollars and many hours to process and split out meaningfully.
• Irrelevance for spam: According to U3HV54286 (Email Geeks Expert), if the core problem is emails going to spam rather than outright bouncing, SMTP logs are generally not helpful because the receiving server typically accepts the message.
• Gmail filtering emphasis: Experts frequently state that Gmail's spam problems, especially those resulting in placement in the bulk or promotions folder, are almost never related to the IP address but are more about domain reputation and message content, including links.
• Consulting without logs: U3HV54286 (Email Geeks Expert) indicates they have learned to perform deliverability consulting effectively without relying heavily on detailed logs because they are so rarely available or useful for certain problems.

Key findings

• Bounce types defined: Documentation differentiates between hard bounces (permanent failures, like invalid addresses) and soft bounces (temporary issues, like full inboxes), each requiring distinct handling for list management.
• Authentication standards: Industry best practices and documentation strongly recommend setting up SPF, DKIM, and DMARC records to authenticate your domain. This verifies sender identity and reduces the likelihood of emails being marked as spam or rejected.
• Reputation's role: ISPs rely heavily on a sender's reputation, built on factors such as bounce rates, spam complaints, and user engagement, to determine whether an email reaches the inbox or the spam folder. A poor reputation can lead to emails being filtered out.
• Log vs. dashboard data: While raw logs contain granular data, ESP documentation often highlights that their built-in deliverability dashboards offer summarized, actionable insights into campaign performance, including overall bounce rates and spam complaint rates, which are easier to interpret.