What does the Gmail 'This message seems dangerous' alert mean for email deliverability?
Matthew Whittaker
Co-founder & CTO, Suped
Published 8 Aug 2025
Updated 19 Aug 2025
9 min read
The 'This message seems dangerous' alert in Gmail is a critical indicator of potential email deliverability issues. It's not just a minor notification; it's a prominent red banner designed to warn recipients about suspicious content, links, or sender behavior. When this alert appears, it signals that Gmail's sophisticated algorithms have identified characteristics commonly associated with phishing scams or malicious messages.
For email marketers and businesses, seeing this warning is a serious concern. It directly impacts whether your emails reach the inbox or are shunted to the spam folder, even if they're legitimate. The presence of this banner drastically reduces recipient trust and engagement, leading to lower open rates, click-through rates, and ultimately, a negative impact on your campaign's effectiveness and brand reputation. Understanding the root causes of this alert is essential for maintaining strong email deliverability.
This guide will explore what this alert means, why it appears, and how to address the underlying issues to ensure your emails consistently reach their intended recipients without such a damaging warning.
Understanding Gmail's warning system
Gmail employs a multi-layered security system to protect its users from spam, phishing, and malware. When an email triggers the 'This message seems dangerous' banner, it means the system has identified significant indicators that the message might be malicious or deceptive. This is a higher-severity warning compared to the 'Be careful with this message' or 'Gmail couldn't verify that example.com actually sent this message' grey warnings, often implying a stronger suspicion of phishing or harmful content.
The primary goal of this warning is to prevent users from falling victim to scams, particularly phishing attacks. Gmail's systems analyze various signals, including sender reputation, authentication records, email content, and historical data, to assess the trustworthiness of an incoming message. If enough red flags are raised, the email is not immediately blocked, especially in corporate settings where internal policies might override some spam filtering, but it is accompanied by this stark warning.
This robust filtering mechanism is why legitimate emails can sometimes inadvertently trigger the alert. For instance, if an email appears to come from your own domain but is sent via a third-party service without proper authentication, Gmail might flag it as suspicious. The system aims to err on the side of caution to protect users, even if it occasionally results in false positives for well-intentioned senders. This is particularly relevant if you're sending transactional emails or marketing campaigns through different platforms.
The red banner explained
The 'This message seems dangerous' alert is typically a red banner at the top of an email. It warns that similar messages have been marked as phishing scams or that the email contains suspicious links used to steal personal information. It explicitly advises against clicking links or replying with personal data.
Impact on deliverability
Even if the email lands in the inbox (due to internal policies), the warning significantly degrades trust. Recipients are highly unlikely to open or interact with an email flagged as dangerous, leading to low engagement metrics and potentially increasing spam complaints, further harming your sender reputation.
Common triggers for the dangerous message alert
Several factors can cause Gmail to display the 'This message seems dangerous' alert, even for legitimate senders. These often revolve around a perceived lack of trustworthiness or suspicious content patterns.
Poor sender reputation: If your domain or IP address has a history of sending spam, being involved in phishing attempts, or having high complaint rates, Gmail's filters will be more aggressive. A low sender reputation is a primary driver of these warnings.
Authentication failures: Missing or misconfigured email authentication protocols like SPF, DKIM, and DMARC make it difficult for Gmail to verify the sender's legitimacy. This can lead to the system perceiving the email as a spoofing attempt, even if it's not. For example, emails failing DMARC verification are highly susceptible to such warnings.
Suspicious content or links: Emails containing unusual or shortened URLs, links to suspicious websites, or content commonly associated with scams (e.g., urgent requests for personal information, financial offers) are often flagged. Even mismatched URLs, where the visible text doesn't match the linked destination, can trigger a phishing warning.
Spoofing or perceived impersonation: If an email appears to come from your own domain but originates from an unfamiliar sending server, Gmail might identify it as a spoofing attempt. This is especially common when sending internal communications through external email marketing platforms.
Another often overlooked factor is when new email templates are introduced or if there are sudden changes in sending volume or patterns, which can temporarily impact how Gmail perceives your emails.
Strategies to prevent the warning
To prevent the 'This message seems dangerous' alert, a multi-faceted approach focusing on authentication, reputation, and content is crucial. Establishing trust with mailbox providers like Gmail is key to consistent inbox placement.
Implement strong email authentication: Ensure your SPF, DKIM, and DMARC records are correctly configured and aligned. DMARC, in particular, signals to Gmail how to handle emails that fail authentication. Start with a p=none policy to monitor first, then gradually move to quarantine or reject.
Monitor your sender reputation: Regularly check your domain and IP reputation using tools like Google Postmaster Tools. Pay attention to spam rates and domain reputation scores. Address any issues promptly.
Review email content and links: Avoid spam trigger words, excessive use of exclamation points, or overly aggressive sales language. Ensure all links are reputable, match their display text, and point to secure (HTTPS) domains. Avoid redirects that obscure the final destination.
Maintain a clean email list: Regularly remove inactive or invalid email addresses to reduce bounce rates and avoid spam traps. A high rate of invalid recipients signals poor list hygiene and can negatively affect your sender reputation.
Warm up new IPs/domains: If you're using a new sending IP or domain, gradually increase your sending volume to build a positive reputation. Sudden high volumes from unfamiliar sources can trigger spam filters and blocklists.
Proactive monitoring and adherence to email best practices are paramount to navigating Gmail's sophisticated filtering systems and ensuring your messages achieve optimal deliverability. Consider using a blocklist checker and DMARC monitoring to stay informed.
Before
No DMARC record: No DMARC record published on the domain.
Mismatched links: Display text for links does not match the actual URL.
High bounce rates: Sending to outdated or invalid email lists frequently.
Consistent link display: All links are clearly displayed and match their destination URLs.
Validated email lists: Regular list cleaning and validation to minimize bounces.
The impact on your business
The appearance of the 'This message seems dangerous' alert has significant repercussions for businesses. It's not merely a deliverability hurdle; it's a direct attack on your brand's credibility and the effectiveness of your email communications.
Erosion of trust: When recipients see a stark red warning, they immediately question the legitimacy of the sender and the message. This can severely damage the trust you've built with your audience, making them hesitant to open future emails, even if the warning is eventually resolved.
Reduced engagement and conversions: A message flagged as dangerous will likely be ignored or deleted without being opened. This directly translates to lower open rates, fewer clicks on your calls to action, and ultimately, a significant drop in conversions, whether for sales, leads, or information dissemination.
Increased spam complaints: Even if an email makes it to the inbox with the warning, recipients might mark it as spam out of caution. A rise in spam complaints sends a strong negative signal to Gmail and other mailbox providers, further exacerbating your sender reputation issues and leading to more emails landing in the spam folder (or junk folder) in the future.
Potential for blocklisting (blacklisting): Consistent warnings and high spam complaint rates can lead to your sending IP or domain being added to email blocklists (also known as blacklists). Once on a blocklist, your emails will be entirely rejected by many mail servers, preventing them from reaching any recipient, not just those using Gmail. This can significantly impact your entire email program and requires active blocklist monitoring and remediation.
Addressing these warnings promptly is vital. Ignoring them can lead to a downward spiral in your email deliverability, where fewer emails reach the inbox, further harming your reputation, and making recovery increasingly difficult. It's an issue that demands immediate attention and a commitment to best practices.
Securing your email's path to the inbox
The 'This message seems dangerous' alert on Gmail is a clear signal that something in your email program needs attention. While it can be frustrating, especially if your emails are legitimate, it also presents an opportunity to strengthen your email security and deliverability practices.
By proactively implementing and monitoring email authentication protocols like SPF, DKIM, and DMARC, maintaining a pristine sender reputation, and ensuring your email content is clean and transparent, you can significantly reduce the likelihood of these warnings. Remember, deliverability is an ongoing effort that requires consistent attention to detail and adherence to evolving email ecosystem standards. Prioritizing these aspects ensures your messages land in the inbox, fostering trust and driving engagement for your brand.
Views from the trenches
Best practices
Always align your email domains with SPF and DKIM for optimal authentication.
Regularly monitor your domain's sending reputation using Google Postmaster Tools.
Ensure all links in your emails are legitimate, secure, and clearly displayed.
Segment your email lists and send targeted content to improve engagement.
Implement DMARC with a monitoring policy to gain visibility into your email ecosystem.
Common pitfalls
Sending emails from a domain without proper SPF, DKIM, or DMARC authentication.
Including generic or suspicious links that don't match the display text.
Ignoring high bounce rates, which indicates poor list quality and harms reputation.
Having sudden spikes in sending volume from new IPs without proper warm-up.
Using content or subject lines that resemble phishing attempts or spam.
Expert tips
Set up a feedback loop with major mailbox providers to quickly detect and address spam complaints.
Utilize a robust email testing tool to preview how your emails appear across different clients.
Regularly audit your third-party sending services to ensure they adhere to best practices.
Consider BIMI implementation for added brand recognition and trust in the inbox.
For transactional emails, prioritize dedicated IPs and strict authentication.
Marketer view
Marketer from Email Geeks says: Test emails sent through MailChimp can sometimes trigger these warning messages, so it's important to differentiate them from live campaign issues.
2018-10-07 - Email Geeks
Marketer view
Marketer from Email Geeks says: This newer, more prominent red banner replaces a smaller, less noticeable alert that Gmail used to display for suspicious messages.
Gmail is a critical indicator of potential email deliverability issues. It's not just a minor notification; it's a prominent red banner designed to warn recipients about suspicious content, links, or sender behavior. When this alert appears, it signals that Gmail's sophisticated algorithms have identified characteristics commonly associated with phishing scams or malicious messages.
