Summary
Emails trigger Gmail phishing warnings due to a combination of factors including compromised accounts, poor sender reputation, lack of email authentication (SPF, DKIM, DMARC), suspicious email content and link structure, use of URL shorteners, and mismatched hostnames in links. Gmail's machine learning identifies these issues. Solutions involve securing accounts, monitoring and improving sender reputation, implementing proper authentication, creating transparent and trustworthy content, using direct URLs, avoiding deceptive coding, managing sending volume, and providing clear sender information. User engagement is crucial for inbox placement.
Key findings
- Bad Hosts/Compromised Machines: Linking to bad hosts or compromised machines, and pages requesting PII suspiciously triggers warnings.
- Machine Learning: Gmail uses machine learning to identify phishing emails.
- Suspicious Content: Suspicious email content (scare tactics, urgent language), and deceptive coding contribute to phishing flags.
- URL Shorteners: Using URL shorteners masks link destinations and raises suspicion.
- Mismatched Hostnames: Mismatched hostnames in links (different display text and URL) are a negative signal.
- Compromised Accounts: Compromised email accounts lead to deliverability problems and phishing warnings.
- Sender Reputation: Poor sender reputation (domain and IP) contributes to phishing flags.
- Email Authentication: Lack of proper email authentication (SPF, DKIM, DMARC) makes verification difficult.
- Sending Volume: Excessive sending volume can trigger phishing detections.
- Email Testing: Using email testing tools and seed list testing platforms can help you to test the mail and check for common spam triggers
- Click Tracking: Disabling click tracking and open tracking will affect the likelihood of emails going into spam/phishing as URL rewriting affects the trust.
- User engagement: User engagement with emails is critical for Gmail deliverability; testing accounts are not representative.
Key considerations
- Secure Accounts: Identify and remediate any compromised accounts on your sending infrastructure.
- Improve Reputation: Monitor and improve your sender reputation (domain and IP) using tools like Google Postmaster Tools.
- Implement Authentication: Set up SPF, DKIM, and DMARC records to authenticate your emails.
- Create Trustworthy Content: Avoid scare tactics, urgent language, deceptive coding, and suspicious PII requests.
- Use Direct URLs: Use direct URLs instead of URL shorteners and ensure linked content is safe.
- Match Hostnames: Ensure display text and underlying URLs of links match to avoid suspicion.
- Manage Sending Volume: Adjust your sending volume to resemble more natural, personal email patterns.
- Clear sender Information: Provide clear and complete sender information in all emails.
- Test Emails: Use testing tools to check for common spam triggers before sending emails.
- User Engagement: Prioritise user engagement by sending valuable and relevant content.
- Disable Click Tracking: Consider disabling click tracking or open tracking to minimise trust issues associated with URL rewriting.
What email marketers say
10 marketer opinions
Emails can trigger Gmail phishing warnings due to various factors related to sender reputation, authentication, content, and link structure. Poor domain or IP reputation, lack of proper email authentication (SPF, DKIM, DMARC), deceptive content, and suspicious links are common causes. Additionally, sending volume, incomplete sender information, and incorrect DKIM setup can contribute to the issue. Maintaining a good sender reputation, ensuring proper authentication, avoiding deceptive practices, and providing clear sender information are key to resolving these warnings.
Key opinions
- Authentication: Proper email authentication (SPF, DKIM, DMARC) is crucial to verify sender legitimacy and prevent spoofing.
- Content: Deceptive content, scare tactics, and urgent language can trigger phishing warnings.
- Sender Reputation: Maintaining a good sender reputation (IP and domain) is essential to avoid being blacklisted.
- Links: Suspicious links, including shortened URLs and mismatched display text, can lead to phishing flags.
- Sending Volume: High sending volume, especially if not resembling personal email patterns, can trigger warnings.
- Sender Info: Providing clear and complete sender information is crucial for building trust.
- Domain/URL reputation: Sending domain or URL in the content might be associated with bad behavior.
- Email Testing: Email testing tools and seed list testing platforms can help you to test the mail and check for common spam triggers
- Click Tracking: Disabling click tracking and open tracking will affect the likelihood of emails going into spam/phishing as URL rewriting affects the trust.
Key considerations
- Implement Authentication: Set up SPF, DKIM, and DMARC records to authenticate your sending domain and verify your emails.
- Review Content: Avoid using scare tactics, urgent language, or deceptive coding in your email content.
- Monitor Reputation: Regularly monitor your sender reputation using tools like Google Postmaster Tools and address any issues promptly.
- Use Direct URLs: Use full, direct URLs instead of URL shorteners and ensure the linked content is trustworthy.
- Adjust Sending Volume: Gradually increase your sending volume and avoid sending too many emails at once, especially when starting with a new IP or domain.
- Provide Clear Information: Ensure your "From" name and email address are easily recognizable, and include a physical address in your email footer.
- Test Your Emails: Use email testing tools and seed list testing platforms to test the mail and check for common spam triggers.
- Disable Click Tracking: Consider disabling click tracking or open tracking to minimise trust issues associated with URL rewriting.
Marketer view
Email marketer from Reddit explains that one reason for phishing flags could be the use of URL shorteners. These can mask the true destination of a link, which raises suspicion. Using the full, direct URL is better, and ensuring the linked content is trustworthy is essential.
28 Jul 2023 - Reddit
Marketer view
Email marketer from Stack Overflow advises checking that your DKIM (DomainKeys Identified Mail) setup is correct. Incorrect DKIM records can cause authentication failures, leading to phishing flags. Use online DKIM validators to verify your record.
13 Jun 2024 - Stack Overflow
What the experts say
8 expert opinions
Emails trigger Gmail phishing warnings due to factors like linking to bad hosts or compromised machines, suspicious requests for personal information, content and link structure issues, using bare hostnames in links, compromised accounts, and poor domain/IP reputation. Proper authentication (SPF, DKIM, DMARC) and user engagement are critical for deliverability. Fixing compromised accounts and improving domain reputation are also essential.
Key opinions
- Bad Hosts/Compromised Machines: Linking to bad hosts or compromised machines is a major cause of phishing warnings.
- Suspicious PII Requests: Linking to pages requesting Personally Identifiable Information (PII) in a suspicious manner triggers warnings.
- Link Structure: Poor content and link structure contribute to phishing warnings.
- Bare Hostnames: Using bare hostnames in links (display text differing from the actual URL) is a significant negative signal.
- User Engagement: User engagement with emails is critical for Gmail deliverability; testing accounts are not representative.
- Compromised Accounts: Compromised accounts lead to deliverability problems and phishing warnings.
- Domain/IP Reputation: Poor domain and IP reputation results in phishing warnings and deliverability issues.
- Authentication: Proper authentication (SPF, DKIM, DMARC) is essential to verify sender legitimacy.
Key considerations
- Review Linked Hosts: Ensure links point to reputable and secure hosts.
- Avoid Suspicious Requests: Do not link to pages that suspiciously request personal information.
- Correct Link Structure: Ensure proper content and link structure, avoiding deceptive practices.
- Avoid Bare Hostnames: Avoid using bare hostnames in links; ensure display text matches the URL destination.
- Focus on Engagement: Prioritize user engagement by sending valuable and relevant content.
- Secure Accounts: Identify and remediate any compromised accounts on your sending infrastructure.
- Monitor Reputation: Regularly monitor your domain and IP reputation using tools like Google Postmaster Tools.
- Implement Authentication: Implement SPF, DKIM, and DMARC to authenticate your sending domain.
Expert view
Expert from Email Geeks explains that linking to bad hosts or compromised machines are major causes of phishing warnings in Gmail. Also, linking to a page requesting PII in a suspicious manner can trigger warnings.
15 Aug 2021 - Email Geeks
Expert view
Expert from Email Geeks suggests that email content and link structure, especially linking to bad hosts, are likely causes for phishing warnings. He emphasizes the importance of alt tags and the need to put them back.
27 Aug 2022 - Email Geeks
What the documentation says
5 technical articles
Emails trigger Gmail phishing warnings due to various factors identified by machine learning, including suspicious links, requests for personal information, and deceptive content. Implementing proper email authentication (SPF, DKIM, DMARC) is crucial for verifying sender legitimacy and preventing spoofing. Services like Microsoft Safe Links rewrite URLs to check for malicious sites. To prevent triggering warnings, ensure clear and legitimate links, avoid asking for sensitive data, maintain transparent communication, and set up accurate SPF records and strict DMARC policies.
Key findings
- Machine Learning: Gmail uses machine learning to identify phishing emails.
- Suspicious Elements: Suspicious links, requests for personal information, and deceptive content trigger phishing warnings.
- SPF Records: SPF records verify the sending mail server's authorization to send emails on behalf of your domain.
- DMARC Policy: DMARC allows setting a policy for handling emails that fail SPF and DKIM checks.
- DKIM: DKIM verifies the domain name identity and message integrity using cryptographic signatures.
- Safe Links: Safe Links rewrites URLs to check for malicious sites before the user accesses them.
Key considerations
- Ensure Clear Links: Use clear and legitimate links in your emails.
- Avoid Sensitive Data Requests: Avoid asking for sensitive personal information in emails.
- Maintain Transparency: Maintain transparent and clear communication in your emails.
- Set Up SPF: Ensure your SPF record accurately lists all legitimate sending sources.
- Implement DMARC: Implement a strict DMARC policy to prevent email spoofing.
- Ensure DKIM: Implement DKIM
- URL Redirects: Avoid creating URL redirects as this can also trigger warnings.
Technical article
Documentation from DMARC.org describes that DMARC (Domain-based Message Authentication, Reporting & Conformance) allows you to set a policy for how receiving mail servers should handle emails that fail SPF and DKIM checks. Implementing a strict DMARC policy (e.g., reject) helps prevent email spoofing and protects your domain's reputation.
14 Jul 2024 - DMARC.org
Technical article
Documentation from IETF describes that DKIM (DomainKeys Identified Mail) is used to verify the domain name identity of an email sender and the integrity of the message. It provides a cryptographic signature that can be validated by the recipient's mail server, helping to prevent email spoofing and phishing attacks.
21 Apr 2023 - IETF
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