Why are my transactional emails from Sendgrid being flagged as spam in Gmail, and how can I fix it?

Key findings

• Gmail's filtering: Gmail utilizes its own reputation and filtering systems, based on unique rules and machine learning, which can categorize emails differently than other spam checks. Even if your emails are delivered, they might still be routed to secondary inboxes or spam.
• Phishing warnings: A common reason for transactional emails going to spam is Gmail's phishing warning (Similar messages have been used to steal users’ personal information.). This warning is triggered by content, links, or even the landing page design.
• Content and links: Adding links (e.g., product links to a renewal email) can alter the email's perceived intent, potentially moving it from transactional to promotional, which may trigger spam filters or phishing warnings due to content similarity with known spam.
• Sender reputation:Poor domain reputation (Gmail stating lots of messages from <domain> are spam) or receiving excessive This is Spam votes from recipients can lead to blocklisting.

Key considerations

• Content review: Thoroughly review email content, especially if new links or elements have been added. Avoid content commonly associated with spam or phishing attempts.
• Landing page structure: If emails contain links, assess the linked landing pages. Simplistic landing pages (e.g., just a login box) can sometimes trigger phishing warnings.
• Email classification: Ensure emails classified as transactional genuinely are. Promotional content within transactional emails can lead to misclassification and spam flagging.
• Authentication and links: Verify your email authentication, including SPF, DKIM, and DMARC. Also, check how your ESP (like SendGrid) wraps click-through links, as generic tracking domains can impact reputation. Using a dedicated domain for link tracking is often beneficial. For more detailed troubleshooting, refer to our guide on how to troubleshoot transactional emails going to spam.

Key opinions

• Not an ESP issue: Many marketers agree that the ESP itself, such as SendGrid, isn't usually the direct cause of spam flagging, implying the problem lies with the email's content or sender practices.
• Audience behavior: If only a specific stream of emails (like transactional) is being blocked, the audience for that particular stream might be the root of the problem due to high complaint rates or low engagement.
• Content similarity: Gmail often flags emails if they are similar to past messages identified as spam, indicating issues with content, templates, or recipient spam complaints.
• Perceived transactional misuse: Adding marketing-like elements (e.g., product links to a renewal email) can cause Gmail to no longer categorize the email as truly transactional, leading to different filtering rules applying and potential spam placement.

Key considerations

• Email content scrutiny: If issues persist, thoroughly review the email content. Even minor changes, such as adding too many links or certain keywords, can impact deliverability. See our guide on why important product emails go to spam.
• Phishing label assessment: If Gmail shows a phishing warning (Similar messages have been used to steal personal information), investigate both the email's content and the linked landing page's design. Minimalistic landing pages might trigger such warnings.
• Re-evaluate campaign goals: For re-engagement campaigns, consider if they truly qualify as transactional. If not, treating them as standard marketing emails with appropriate opt-in and consent may prevent spam flagging.
• Leverage testing tools: Use tools like aboutmy.email to compare email characteristics from different sending setups (e.g., transactional vs. marketing ESPs). This can help identify subtle differences in link wrapping, headers, or authentication that Gmail might be reacting to. Remember, a comprehensive approach is vital, as highlighted in general deliverability advice.

Key opinions

• Phishing label nuance: The this might be phishing warning from Google is not a standard deliverability problem but a content-driven issue. It can be influenced by the appearance of the linked landing page, for instance, a minimalistic login page versus a standard web page.
• Content and landing pages: Both the email's content and the linked landing page's appearance can trigger Gmail's phishing filter, even if the content remains unchanged. This is often an overlooked aspect of deliverability.
• Campaign re-evaluation: If a campaign receives phishing warnings, it might be necessary to completely rethink the approach, especially if trying to pass marketing emails as transactional. This can also impact your sender reputation.
• Link and authentication differences: Different ESPs (like SendGrid vs. a marketing ESP) wrap click links and manage asset links differently, and their authentication setups will vary. These distinctions can significantly affect how Gmail processes the email. Always ensure your authentication records are correctly configured.

Key considerations

• Comprehensive analysis: Use diagnostic tools (e.g., aboutmy.email) to send emails from all affected setups and compare the results meticulously. Pay close attention to link wrapping, authentication details, and the overall email payload to pinpoint discrepancies.
• Transactional vs. marketing: Clearly differentiate between transactional and marketing emails. If an email's purpose isn't strictly transactional, it might be better handled by a marketing email system to avoid triggering stricter spam filters for transactional streams.
• Landing page optimization: For emails with links, ensure that the landing pages are well-developed, with sufficient text and context, to avoid appearing suspicious to Gmail's algorithms.
• Proactive monitoring: Continuously monitor email performance and Gmail's responses to messages. Being proactive in identifying changes in deliverability patterns can help address issues before they escalate, as general best practices often advise. Staying informed on deliverability trends is crucial.

Key findings

• Authentication failures: Gmail is likely to block emails if they fail authentication checks (SPF, DKIM, DMARC), a primary reason for messages not reaching the inbox.
• Domain flagging: Your domain being flagged as spam by Gmail's internal systems is a significant factor in deliverability issues, indicating broader reputation problems. This is distinct from being on a public blacklist or blocklist.
• Content quality: Emails similar to past identified spam, or those with suspicious content (e.g., specific phrases or layouts that mimic phishing attempts), are highly likely to be filtered, even if technically transactional.
• IP and domain reputation: Your IP address or domain being on a blocklist, or having a low sender reputation, directly influences whether emails reach inboxes or spam folders. This applies even if other technical configurations are correct.

Key considerations

• Authentication standards: Prioritize robust email authentication (SPF, DKIM, DMARC) for your sending domain. Regular checks using tools like Google Postmaster Tools are essential to monitor your domain's health and authentication status.
• Sender reputation management: Maintain a healthy sender reputation by minimizing spam complaints, avoiding sending to unengaged users, and using confirmed opt-in practices. Unreliable providers or shared hosting IPs can negatively impact your reputation.
• Content best practices: Ensure your email content adheres to anti-spam guidelines. This includes avoiding deceptive phrasing, excessive capitalization, and certain attachment types. For transactional emails, keep the content concise and directly related to the transaction.
• Compliance with policies: Stay updated with and comply with major mailbox provider requirements. Gmail and other providers frequently update their policies, impacting even transactional emails. Refer to official ESP documentation and guidelines to ensure adherence.