Summary
Transactional emails from SendGrid often land in spam while campaign emails reach the inbox due to a multifaceted combination of factors. These include poor IP reputation stemming from shared IPs or lack of proper IP warm-up, content characteristics that trigger spam filters, missing or incorrect header information, and sending volume patterns such as sudden bursts from new IPs. Authentication issues (SPF, DKIM, DMARC), higher spam rates, the absence of feedback loops, and a low sender reputation also contribute significantly. Furthermore, engagement metrics such as low open and click-through rates, the lack of a double opt-in strategy, poor email list hygiene, Gmail's sophisticated fingerprinting techniques, and individual inbox training through behaviors like deleting test emails without engagement play critical roles. Finally, different configurations applied by inbox providers can affect the emails.
Key findings
- IP Reputation: Transactional emails often suffer from poor IP reputation due to shared IPs or lack of warm-up.
- Content Filtering: Transactional emails' content and patterns can trigger spam filters, especially with specific keywords.
- Header Issues: Missing or incorrect header information in transactional emails can negatively impact deliverability.
- Sending Volume: Sudden bursts of transactional emails, especially from new IPs, can trigger spam filters.
- Authentication: Transactional emails often lack proper authentication (SPF, DKIM, DMARC) configurations.
- Spam Rate: A higher spam rate for transactional emails can cause them to be classified as spam.
- Feedback Loops: The absence of feedback loops leads to deliverability issues.
- Sender Reputation: A low sender reputation results in emails being filtered or blocked.
- Engagement Metrics: Lower engagement metrics (open and click-through rates) can negatively impact deliverability.
- Double Opt-In: Lack of a double opt-in strategy can hurt email deliverability.
- List Hygiene: Poor email list hygiene (unengaged or inactive contacts) affects deliverability.
- Gmail Fingerprinting: Gmail can differentiate sends based on content, headers, and cadence.
- Inbox Training: Deleting test emails without engagement can train inboxes to mark emails as spam.
- Configurations: Differences in configurations applied by inbox providers affect deliverability
Key considerations
- IP Management: Consider using a dedicated IP for transactional emails and properly warming it up.
- Content Optimization: Review and optimize the content of transactional emails to avoid triggering spam filters.
- Header Verification: Ensure that all necessary header fields are correctly configured.
- Volume Ramp-Up: Gradually increase the sending volume to avoid triggering spam filters.
- Implement Authentication: Ensure correct SPF, DKIM, and DMARC settings are configured.
- Monitor Spam Rate: Monitor spam rate and maintain it below the threshold.
- Implement Feedback Loops: Implement feedback loops to improve sender reputation.
- Monitor Reputation: Track sender reputation and make sure it is high.
- Improve Engagement: Focus on improving engagement metrics.
- Implement Opt-In: Implement a double opt-in strategy.
- Improve List Hygiene: Regularly clean the email list.
- Review Configurations: Review all necessary configurations and ensure they are properly setup.
What email marketers say
9 marketer opinions
Transactional emails often end up in spam while campaign emails reach the inbox due to several factors. These include differences in IP reputation (shared vs. dedicated, warm-up), content (patterns triggering filters), header information (missing or incorrect fields), sending volume (sudden bursts), and engagement metrics. Other factors include fingerprinting by Gmail, lack of a double opt-in strategy, and poor email list hygiene practices.
Key opinions
- IP Reputation: Transactional emails often suffer from poor IP reputation due to shared IPs or lack of warm-up, whereas campaign emails may benefit from dedicated IPs.
- Content Filtering: Transactional emails' content and patterns can trigger spam filters, especially with specific keywords related to transactions.
- Header Issues: Missing or incorrect header information in transactional emails can negatively impact deliverability.
- Sending Volume: Sudden bursts of transactional emails, especially from new IPs, can trigger spam filters.
- Gmail Fingerprinting: Gmail can identify and differentiate between types of sends through content, headers and cadence.
- Engagement Metrics: Transactional emails often have lower open and click-through rates than campaign emails, making inbox providers view them less favorably.
- Double Opt-In: Lack of a double opt-in strategy can hurt email deliverability and domain authority.
- Email List Hygiene: Poor email list hygiene (unengaged or inactive contacts) affects deliverability.
Key considerations
- IP Management: Consider using a dedicated IP for transactional emails and properly warming it up to establish a good reputation.
- Content Optimization: Review and optimize the content of transactional emails to avoid triggering spam filters.
- Header Verification: Ensure that all necessary header fields are correctly configured in transactional emails.
- Volume Ramp-Up: Gradually increase the sending volume of transactional emails to avoid triggering spam filters.
- Engagement: Try and improve engagment rates in Transactional emails to gain better reputation
- Double Opt-in: Use a double opt-in system to show inbox providers that your contacts want to receive emails.
- Hygiene Practices: Regularly clean your email list and remove unengaged contacts to improve deliverability.
Marketer view
Marketer from Email Geeks shares he's seen this happen a lot (I assume you mean gmail). Not sure exactly what it is but gmail is fantastic at fingerprinting certain sends. Could be the headers, could be the content, could be the cadence, but they can tell the difference.
27 Jul 2021 - Email Geeks
Marketer view
Email marketer from Gmass shares that not having a Double Opt-In strategy can hurt your email deliverability and domain authority. Double opt-in can show inbox providers that your contacts actually want to receive emails from you, greatly reducing your spam complaints and boosting sender reputation.
25 Mar 2022 - Gmass
What the experts say
4 expert opinions
Transactional emails from SendGrid might land in spam due to several factors. Repeatedly deleting test emails without engagement can train your inbox to flag them as spam. Incorrect or missing authentication settings (SPF, DKIM, DMARC) may cause email providers to view transactional emails as suspicious. Additionally, lower engagement metrics, such as open and click-through rates, compared to campaign emails can negatively impact deliverability. Differences in configurations applied by inbox providers, such as missing feedback loops, can also contribute to spam placement.
Key opinions
- Inbox Training: Deleting test emails without engagement can train your inbox to mark them as spam.
- Authentication Settings: Missing or incorrect authentication settings (SPF, DKIM, DMARC) can cause email providers to flag transactional emails as suspicious.
- Engagement Metrics: Lower engagement metrics (open and click-through rates) can negatively impact deliverability.
- Configuration Differences: Missing configurations, such as feedback loops, can cause inbox providers to view emails less favorably.
Key considerations
- Test Email Engagement: Avoid repeatedly deleting test emails; engage with them instead.
- Authentication Setup: Ensure correct SPF, DKIM, and DMARC settings are configured for transactional emails.
- Engagement Improvement: Focus on improving engagement metrics (open and click-through rates) for transactional emails.
- Configuration Review: Verify that all necessary configurations, including feedback loops, are properly set up.
Expert view
Expert from Word to the Wise responds that inbox providers treat emails differently depending on the configurations applied. Some configurations may be missing on some emails, such as authentication or feedback loops. This creates a problem when the inbox providers treat your emails more favorably when they can determine they are legitimate through configurations.
24 Dec 2022 - Word to the Wise
Expert view
Expert from Email Geeks suggests looking at authentication settings.
15 Dec 2022 - Email Geeks
What the documentation says
4 technical articles
Transactional emails from SendGrid may end up in spam due to a combination of technical configurations and reputation issues. Lack of proper email authentication (SPF, DKIM, DMARC) is a significant factor. Additionally, a higher spam rate for transactional emails, as tracked by Google Postmaster Tools, can lead to Gmail classifying them as spam. The absence of feedback loops, which notify senders when recipients mark emails as spam, also contributes to deliverability problems. Furthermore, a low sender reputation, as perceived by Microsoft, can result in emails being filtered to junk or blocked entirely.
Key findings
- Authentication Issues: Transactional emails often lack proper authentication (SPF, DKIM, DMARC) configurations.
- High Spam Rate: A higher spam rate for transactional emails can cause Gmail to classify them as spam.
- Lack of Feedback Loops: The absence of feedback loops leads to deliverability issues.
- Low Sender Reputation: A low sender reputation, as determined by Microsoft, results in emails being filtered or blocked.
Key considerations
- Implement Authentication: Ensure correct SPF, DKIM, and DMARC settings are configured for transactional emails.
- Monitor Spam Rate: Monitor your spam rate using Google Postmaster Tools and maintain it below the threshold.
- Implement Feedback Loops: Implement feedback loops to improve sender reputation and deliverability.
- Monitor Sender Reputation: Track your sender reputation using Microsoft's Smart Network Data Services (SNDS).
Technical article
Documentation from RFC explains that a lack of feedback loops for transactional emails can lead to deliverability issues. Feedback loops allow email providers to notify senders when recipients mark their emails as spam. Implementing feedback loops helps improve sender reputation and deliverability.
16 Apr 2025 - RFC Documentation
Technical article
Documentation from Microsoft explains that if your sender reputation is low, then Microsoft is more likely to filter your emails straight to the junk folder or block your email altogether. Use Microsoft's Smart Network Data Services (SNDS) to track your reputation.
12 Feb 2023 - Microsoft Documentation
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