Summary
Recent drops in Gmail deliverability are influenced by a complex interplay of factors, necessitating detailed data analysis for accurate diagnosis. Key contributors include poor sender reputation (resulting from low engagement, high bounce rates, and spam complaints), inadequate email authentication (SPF, DKIM, DMARC), and non-compliance with Gmail's bulk sending guidelines. Engagement is crucial, as Gmail prioritizes emails deemed valuable to recipients. Poor list hygiene, spam trigger words in content, shared IPs with bad reputations, exceeding sending limits, and failure to properly warm up new IPs all contribute. Senders must adapt to Gmail's evolving spam filters and be aware of new sending requirements such as easy unsubscribe options. List bombs, where many spam reports are received in a short time, will affect deliverability.
Key findings
- Detailed Data Analysis: The complexity of Gmail's blocking mechanisms requires detailed data analysis and careful examination of bounce messages.
- Sender Reputation: Low engagement, high bounce rates, and spam complaints significantly damage sender reputation.
- Authentication Protocols: Lack of proper SPF, DKIM, and DMARC authentication leads to increased spam filtering.
- Gmail Guidelines: Non-compliance with Google's bulk sending guidelines results in deliverability issues.
- List Hygiene: Sending to inactive or invalid email addresses degrades sender reputation.
- Content Triggers: Spam trigger words, broken HTML, and poor text-to-image ratios flag emails as spam.
- IP Reputation: Sharing an IP with a poor reputation negatively impacts deliverability.
- Sending Limits: Exceeding Gmail's daily sending limits can lead to temporary blocks and spam filtering.
- IP Warm-up: Failure to gradually warm up a new IP address triggers spam filters.
- Engagement Matters: Gmail favors senders who have positive engagement.
- List Bombs: Sudden spikes in spam complaints will negatively impact deliverability.
- Sending Requirements: New sending requirments such as authentication and unsubscription are required.
Key considerations
- Analyze Data: Regularly analyze sending data and bounce messages to identify and address deliverability issues.
- Improve Reputation: Implement strategies to improve sender reputation, such as boosting engagement and reducing bounce rates.
- Implement SPF, DKIM, DMARC: Properly configure SPF, DKIM, and DMARC to authenticate your email and prevent spoofing.
- Adhere to Gmail's Guidelines: Familiarize yourself with and follow Google's bulk sending guidelines.
- Maintain List Hygiene: Regularly clean your email list by removing inactive, invalid, or unengaged subscribers.
- Optimize Email Content: Review your email content for spam trigger words and ensure proper HTML formatting.
- Monitor IP Reputation: Check your IP reputation and take steps to address any negative issues.
- Respect Sending Limits: Stay within Gmail's daily sending limits.
- Warm Up New IPs: If using a new IP, gradually increase sending volume over time.
- Check for Sudden Spam Complaints: Be aware of the potential for targeted spam attacks and monitor for sudden spikes in complaints.
- Sending Requirements: Comply with new email sending requirements, including authentication and easy unsubscribe functionality, to maintain good deliverability.
What email marketers say
12 marketer opinions
Gmail deliverability issues causing emails to land in spam are multifaceted. Several factors contribute, including a poor sender reputation stemming from low engagement, high bounce rates, and spam complaints. Inadequate email authentication (SPF, DKIM, DMARC) raises suspicion with Gmail, while using shared IPs with poor reputations can also damage deliverability. Email content containing spam trigger words, broken HTML, or a poor text-to-image ratio increases the likelihood of emails being filtered. Poor list hygiene, such as sending to inactive or invalid addresses, further harms sender reputation. Exceeding Gmail's sending limits or failing to warm up a new IP address gradually can also trigger spam filters. The ongoing 'cat and mouse' game with spam filters requires constant adaptation, including cutting back on unengaged openers and focusing on verifiable engagement metrics.
Key opinions
- Sender Reputation: A poor sender reputation is a primary driver of deliverability problems, influenced by engagement, bounce rates, and spam complaints.
- Authentication: Lack of proper email authentication (SPF, DKIM, DMARC) can cause Gmail to flag emails as suspicious and send them to spam.
- Engagement: Low engagement rates signal to Gmail that emails are not valuable, leading to deliverability issues.
- List Hygiene: Poor list hygiene (inactive/invalid addresses) damages sender reputation and increases spam placement.
- Content Quality: Spam trigger words, broken HTML, and poor text-to-image ratios in email content can trigger spam filters.
- Sending Limits: Exceeding Gmail's sending limits can result in temporary blocks and deliverability problems.
- IP Reputation: Using a shared IP address with a poor reputation can negatively impact deliverability.
- List Bombing: A sudden influx of spam complaints, potentially from a 'list bomb,' can drastically decrease deliverability.
Key considerations
- Monitor Sender Reputation: Actively monitor your sender reputation and address any negative trends promptly.
- Implement Authentication: Ensure proper email authentication (SPF, DKIM, DMARC) is in place to verify your identity.
- Improve Engagement: Focus on improving engagement rates by targeting relevant content to engaged subscribers and cleaning inactive users.
- Practice List Hygiene: Regularly clean your email list to remove invalid or inactive email addresses.
- Optimize Content: Optimize email content to avoid spam trigger words, ensure proper HTML formatting, and maintain a good text-to-image ratio.
- Respect Sending Limits: Adhere to Gmail's sending limits to avoid triggering spam filters.
- Warm Up IPs: If using a new IP address, gradually warm it up to establish a good reputation with Gmail.
- Monitor for Attacks: Watch for unusual activity, such as unexpected surges in spam complaints, which could indicate a targeted attack.
- New Sending Requirements: Be aware of new sending requirements and implement where appropriate such as easy unsubscribe functionality.
Marketer view
Email marketer from StackExchange points out that a shared IP address with a poor reputation can negatively impact deliverability. If other users on the same IP are sending spam, your emails may be affected.
8 Mar 2025 - StackExchange
Marketer view
Email marketer from Reddit shares that they saw deliverability drop after a recent list import. They recommend validating email lists to remove old emails. A lot of soft bounces can cause you to be flagged
8 Jan 2024 - Reddit
What the experts say
4 expert opinions
Recent drops in Gmail deliverability can be attributed to various factors. Pinpointing the exact cause requires a detailed analysis of data and bounce messages due to the complexity of Gmail's blocking mechanisms. One potential reason is a 'list bomb,' characterized by a sudden surge in spam complaints, possibly stemming from outdated lists or targeted attacks. Landing in the Promotions tab, while not spam, can negatively impact email visibility and overall engagement. New sending requirements also affect deliverability. Senders need to authenticate and allow unsubscriptions.
Key opinions
- Diagnostic Complexity: Determining the specific cause of Gmail deliverability issues requires thorough data analysis and examination of bounce messages.
- List Bomb Impact: A 'list bomb' (sudden spike in spam complaints) can significantly harm deliverability.
- Promotions Tab Visibility: Ending up in the Promotions tab, although not classified as spam, reduces email visibility and reading rates.
- New Sending Requirements: Gmail is enforcing new requirements, such as authentication and easy unsubscription options, impacting deliverability.
Key considerations
- Data Analysis: Conduct thorough data analysis and closely examine bounce messages to identify the root cause of deliverability problems.
- List Hygiene: Maintain a clean email list to prevent spam complaints and bounce backs.
- Engagement Focus: Develop strategies to avoid the promotions tab, as this improves email visibility.
- Compliance: Comply with new email sending requirements, including authentication and easy unsubscribe functionality, to maintain good deliverability.
- Attack Awareness: Be aware of the potential for targeted spam attacks and monitor for sudden spikes in complaints.
Expert view
Expert from Email Geeks explains that there isn't enough detail to answer the question, and Gmail blocks for many reasons, some old, some new. Testing and reviewing data is needed, and bounce messages should be read closely to understand what is happening. Research should start there.
9 Nov 2023 - Email Geeks
Expert view
Expert from Spam Resource explains that deliverability can drop due to a 'list bomb' where a large number of spam complaints are generated in a short period. This can happen if your list contains old or unengaged addresses, or if you've been targeted by a spam attack.
25 Jan 2023 - Spam Resource
What the documentation says
4 technical articles
Gmail deliverability issues leading to emails landing in spam are often linked to non-compliance with established email authentication and sending guidelines. Google emphasizes following its bulk sending guidelines, including email authentication, feedback loops, and easy unsubscribe options. SPF records are crucial for identifying authorized mail servers to prevent domain spoofing. DKIM adds a digital signature to verify the sender and prevent email spoofing. DMARC builds upon SPF and DKIM, allowing senders to instruct receiving servers on how to handle emails failing authentication checks, providing an extra layer of protection against spoofing and phishing.
Key findings
- Google Guidelines: Adhering to Google's bulk sending guidelines is critical for maintaining good deliverability.
- SPF Authentication: SPF records are essential for preventing spammers from forging your domain in the 'From' address.
- DKIM Authentication: DKIM signatures help verify the sender's identity and prevent email spoofing.
- DMARC Authentication: DMARC provides an extra layer of protection against spoofing and phishing by instructing receiving servers on how to handle authentication failures.
Key considerations
- Compliance with Guidelines: Review and adhere to Google's bulk sending guidelines to ensure compliance and improve deliverability.
- Implement SPF: Properly configure SPF records to authorize your mail servers and prevent domain spoofing.
- Implement DKIM: Implement DKIM to digitally sign your emails and verify the sender's identity.
- Implement DMARC: Implement DMARC to instruct receiving servers on how to handle emails failing SPF or DKIM checks and prevent spoofing/phishing.
Technical article
Documentation from RFC 4871 explains that DomainKeys Identified Mail (DKIM) is an email authentication method that uses a digital signature to verify the sender and prevent email spoofing. Implementing DKIM can significantly improve deliverability by assuring Gmail that your emails are legitimate.
18 Nov 2024 - RFC 4871
Technical article
Documentation from DMARC.org shares that Domain-based Message Authentication, Reporting & Conformance (DMARC) is an email authentication protocol that allows senders to tell receiving mail servers what to do if an email fails SPF or DKIM checks (e.g., reject, quarantine). Implementing DMARC provides an extra layer of protection against email spoofing and phishing, improving deliverability.
4 May 2025 - DMARC.org
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