Summary
Gmail deliverability issues arise from various factors, broadly categorized into sender reputation, authentication, content, engagement, and infrastructure. A sudden drop in domain/IP reputation, inconsistent sending patterns, high complaint rates, and being blocklisted are significant contributors. Improper authentication (SPF, DKIM, DMARC), sending spam-like bulk emails, and missing PTR records exacerbate the problem. Low engagement, using spam trigger words, and poor list hygiene also play a role. Review ESP error messages, monitor Sender Score, check blocklists, test content using aboutmy.email, warm up new IPs, and ensure consistent sending habits.
Key findings
- Reputation Issues: A sudden decline in domain or IP reputation, as reflected in Sender Score or blocklist status, is a primary cause. Check your reputation regularly.
- Authentication Problems: Improper email authentication (SPF, DKIM, DMARC) is a critical factor. Ensure proper configuration to verify legitimacy.
- Content Quality: Using spam trigger words and sending bulk emails resembling spam negatively impact deliverability. Review email content carefully.
- Engagement Metrics: Decreased engagement (opens, clicks) and high complaint rates signal deliverability problems. Focus on relevant and engaging content.
- List Hygiene: Sending emails to old, unengaged, or invalid addresses harms sender reputation. Practice regular list cleaning.
- Infrastructure Issues: Changes in sending infrastructure (IP, ESP, DNS), or missing PTR records, can cause deliverability problems. Review infrastructure configurations.
- Sending Patterns: Inconsistent sending volumes, spikes or drops, will flag your emails as suspicious.
Key considerations
- Review ESP Errors: Examine specific rejection/deferral messages from your ESP to pinpoint the root cause of deliverability issues.
- Monitor Sender Score: Regularly track your Sender Score and take steps to improve it if it's low.
- Check Blocklists: Verify your IP addresses and domains against common blocklists and promptly address any listings.
- Test Content: Use tools like aboutmy.email to test email content and identify potential issues before sending.
- Warm Up New IPs/Domains: If transitioning to a new IP or domain, gradually warm it up to establish a positive sending reputation.
- Maintain List Hygiene: Regularly clean and segment your email lists to remove unengaged subscribers and invalid addresses.
- Establish consistent sending habits: Maintain a regular and consistent sending pattern to avoid flagging by spam filters.
What email marketers say
9 marketer opinions
Several factors can cause Gmail emails to suddenly go to spam. These include a drop in domain or IP reputation due to changes in sending habits, being on a shared IP, or negative engagement like spam complaints. Using spam trigger words, sending to unengaged contacts, and decreased engagement rates also contribute. Being blocklisted or having a low Sender Score are further reasons. Warming up a new domain/IP gradually and monitoring feedback loops are important considerations.
Key opinions
- Reputation Drop: Sudden declines in domain or IP reputation are significant causes. Check your reputation using available tools.
- Spam Triggers: The content of your emails, including spam trigger words, can cause deliverability problems. Review subject lines and email bodies for problematic terms.
- Engagement Matters: Low engagement rates (opens, clicks) negatively impact deliverability. Focus on relevant and engaging content.
- List Hygiene: Sending to unengaged or invalid email addresses can harm your sender reputation. Regularly clean your email lists.
- Blocklists: Being listed on a blocklist will result in a dramatic decline in deliverability.
- Shared IP: If you're on a shared IP address, the actions of other senders can impact your deliverability.
- Sender Score: Your sender score will affect your deliverability and should be checked regularly.
Key considerations
- Warming Up: If using a new domain or IP, gradually warm it up to establish a positive sending reputation.
- Feedback Loops: Monitor feedback loops from Gmail to identify and address spam complaints promptly.
- Monitor Reputation: Continuously monitor your domain and IP reputation to identify and address issues promptly.
- Check blocklists: Regularly check your IP addresses and domains against common blocklists.
Marketer view
Email marketer from Sender explains that using spam trigger words in your subject line and email body can cause Gmail to send your emails to spam. Review your content for common spam keywords and phrases.
10 Jul 2021 - Sender
Marketer view
Email marketer from Litmus explains that decreased engagement rates (opens, clicks) signal to Gmail that your emails are not valuable to recipients, which can negatively impact deliverability. Focus on sending relevant and engaging content.
29 May 2024 - Litmus
What the experts say
7 expert opinions
Gmail emails may suddenly go to spam due to several factors. Checking ESP rejection/deferral messages is crucial for specific error details. Sending pattern inconsistencies (volume spikes/drops) trigger spam filters. A sudden drop in sender reputation also affects deliverability; use Sender Score to monitor. Recent infrastructure changes (IP, ESP, authentication) or content/engagement issues (complaint rates, broken unsubscribe links) can cause problems. Testing email content and deploying to aboutmy.email helps identify issues.
Key opinions
- ESP Errors: Specific rejection/deferral messages from your ESP (e.g., Klaviyo) provide crucial error details. Investigate ESP logs.
- Sending Patterns: Inconsistent sending volumes can trigger spam filters.
- Sender Reputation: A sudden drop in sender reputation affects deliverability.
- Infrastructure Changes: Recent changes to sending infrastructure (IP, ESP, authentication, DNS) impact deliverability.
- Content & Engagement: Problems with content and engagement like spam complaints and broken unsubscribe links trigger spam filters.
Key considerations
- Check ESP Messages: Review rejection/deferral messages within your ESP to diagnose specific issues.
- Monitor Reputation: Regularly monitor sender reputation using tools like Sender Score.
- Test Content: Test subject lines, content, and unsubscribe links to identify and fix issues.
- Use aboutmy.email: Deploy to aboutmy.email to get insights.
Expert view
Expert from Email Geeks recommends getting an email address from aboutmy.email and using it for a production deployment (not a test) within Klaviyo to gain potential insights into deliverability issues.
2 Mar 2023 - Email Geeks
Expert view
Expert from SpamResource advises checking your sender reputation regularly, as a sudden drop can indicate issues leading to spam classification. Use tools like Sender Score to monitor your reputation.
10 Jan 2024 - SpamResource
What the documentation says
4 technical articles
Gmail employs filters based on sender reputation, authentication (SPF, DKIM, DMARC), user complaints, and sending patterns to determine if an email is spam. Key issues include improper authentication, sudden sending changes, bulk emails resembling spam (deceptive subjects, missing unsubscribe), and missing/incorrect PTR records.
Key findings
- Reputation & Complaints: Gmail filters messages based on sender reputation and user complaints. High complaint rates directly impact spam classification.
- Authentication: Improper email authentication (SPF, DKIM, DMARC) is a primary reason for emails going to spam. Proper authentication verifies legitimacy.
- Bulk Email Best Practices: Bulk emails that resemble spam trigger filters. Deceptive subjects and missing unsubscribe options are red flags.
- PTR Records: Missing or incorrect PTR records (reverse DNS lookup) can cause spam classification. PTR records must match sending IP to domain name.
- Sending Patterns: Sudden changes in sending patterns can cause emails to land in spam.
Key considerations
- Authentication Setup: Ensure correct SPF, DKIM, and DMARC settings to authenticate your domain properly.
- Email Content: Avoid deceptive subject lines and always include a clear unsubscribe option in bulk emails.
- PTR Record Verification: Verify that your sending IP has a valid PTR record pointing to your domain.
- Consistent Sending: Establish and maintain a regular and consistent sending pattern to avoid flagging by spam filters.
Technical article
Documentation from SparkPost details that improper email authentication (SPF, DKIM, DMARC) is a primary reason for emails ending up in spam. Ensure your domain is properly authenticated to verify your legitimacy to mailbox providers.
8 Nov 2024 - SparkPost
Technical article
Documentation from RFC specifies that having a valid PTR record (reverse DNS lookup) that matches your sending IP address to your domain name is crucial for email deliverability. Missing or incorrect PTR records can lead to spam classification.
9 Jul 2022 - RFC
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