Gmail's 'This message seems dangerous' warning is triggered by several factors, primarily related to suspected phishing or malware, sender reputation, and email authentication. Suspicious links, spammy content, and unusual sending patterns are red flags. Authentication failures (SPF, DKIM, DMARC) are a major cause, as are blacklisted domains or IPs, compromised websites, and insecure links. Poor email practices like high bounce rates and spam complaints contribute to low sender reputation. Additionally, link masking, inconsistent sending volumes, and even well-intentioned marketing emails triggering spam filters can result in the warning.
9 marketer opinions
Gmail's 'This message seems dangerous' warning appears primarily due to suspected phishing, malware, or poor sender reputation. Issues include suspicious links, spammy content, authentication failures (SPF, DKIM, DMARC), blacklisted domains or IPs, insecure links/SSL certificates, and poor email practices such as high bounce rates or spam complaints. Consistent sending volumes, avoiding URL shorteners, and maintaining a clean email list are also important factors.
Marketer view
Email marketer from SendPulse Blog responds that the warning could mean that the email failed authentication checks, the sender's IP is blacklisted, or the email content resembles phishing attempts.
15 May 2025 - SendPulse Blog
Marketer view
Email marketer from Google Support explains that the 'This message seems dangerous' warning appears when Gmail suspects phishing or malware. Users should avoid clicking links or providing personal information.
28 Dec 2021 - Google Support
5 expert opinions
Gmail's 'This message seems dangerous' warning can stem from a compromised website hosting malicious content, the use of link masking or redirection services which negatively impacts reputation due to association with malicious activity, or even well-intentioned marketing emails triggering spam filters. Google's Safe Browsing tool and Webmaster Tools are suggested for identifying malicious links. It's essential to maintain a reputable sending infrastructure and avoid deceptive content.
Expert view
Expert from Word to the Wise, that even well-intentioned marketing emails can trigger spam filters and warnings, which could potentially cause a "This message seems dangerous" warning. Ensuring content isn't considered deceptive and uses a reputable sending infrastructure are key to avoiding such issues.
22 Feb 2024 - Word to the Wise
Expert view
Expert from Email Geeks recommends checking Google Webmaster Tools for more data on malicious links.
6 Jan 2023 - Email Geeks
4 technical articles
Gmail's 'This message seems dangerous' warning is frequently caused by failures in email authentication. Properly configured SPF, DKIM, and DMARC records are essential for verifying sender identity and preventing email spoofing. When these authentication standards are missing or improperly implemented, Gmail flags the message as potentially dangerous.
Technical article
Documentation from RFC Editor describes that Sender Policy Framework (SPF) records prevent email spoofing by specifying which mail servers are authorized to send email on behalf of a domain. Misconfigured or missing SPF records can trigger warnings.
28 Oct 2021 - RFC 4408
Technical article
Documentation from DMARC.org outlines that Domain-based Message Authentication, Reporting & Conformance (DMARC) helps email receivers handle messages that fail SPF and DKIM checks, providing a policy for handling such messages (e.g., reject, quarantine). Missing or improperly configured DMARC records can lead to warnings.
23 Oct 2022 - DMARC.org
How can I avoid Gmail security warnings on emails?
How do I troubleshoot Gmail phishing email warnings?
Why are emails from a new .uk domain going to spam folders?
Why are my authenticated emails to Gmail soft bouncing with a DKIM and SPF fail error?
Why did Gmail mark an internal email as potentially dangerous?
Why is Gmail rejecting unauthenticated email from gmail.com due to DMARC policy when sending via Sendgrid?