How to prevent Gmail from marking emails as phishing due to linked login pages?
Matthew Whittaker
Co-founder & CTO, Suped
Published 10 Jul 2025
Updated 19 Aug 2025
6 min read
Emails getting flagged as phishing by Gmail can be a frustrating experience, especially when they contain legitimate links to your login pages. It creates a significant hurdle for user experience and can severely impact your email deliverability. This happens because Gmail's sophisticated algorithms are constantly working to protect users from malicious attacks, including various forms of phishing.
When your emails, particularly those with essential login links, are mistakenly identified as phishing, it leads to decreased engagement, higher bounce rates, and a damaged sender reputation. Understanding the root causes of these warnings and implementing preventative measures is crucial to ensure your messages reach the inbox safely and are trusted by recipients.
Understanding Gmail’s phishing detection
Gmail employs a multi-layered approach to identify and flag potential phishing attempts. It scrutinizes various elements of an email, including the sender's reputation, email authentication, content, and especially the links embedded within the message. If any of these elements raise a red flag, Gmail may issue a warning or even route the email directly to the spam folder.
The warning often appears as a banner stating, "This message seems dangerous." This is a proactive measure to protect users from clicking on links that could lead to compromised sites or credential theft. Even if your intentions are legitimate, certain characteristics of your email or the linked login page might inadvertently mimic phishing tactics, triggering these warnings.
A common scenario involves links to login pages that lack proper security protocols or present themselves in a way that raises suspicion. Google is very clear about protecting users from phishing, as outlined in their phishing prevention guidelines. If a linked page, especially a login page, doesn't meet their security expectations, it's flagged. You can dive deeper into why emails get a phishing warning in Gmail to understand more.
Common triggers for phishing warnings
Unsecured login pages: Pages not using HTTPS will almost certainly trigger warnings.
Suspicious domain reputation: A new domain, one with a history of spam, or one resembling a known phishing site can be flagged. Learn how to recover your domain reputation.
Generic or unbranded login forms: Pages that lack company branding can appear suspicious.
Link shorteners: These are often used in phishing and can trigger warnings.
Mismatch between visible URL and actual URL: Any discrepancy will be flagged.
Strengthening your email authentication
A fundamental step in preventing Gmail from marking your emails as phishing is to ensure robust email authentication. This involves correctly configuring SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance). These protocols verify that your emails are legitimate and haven't been tampered with, significantly boosting your sender trustworthiness.
Implementing DMARC
DMARC is particularly important as it tells receiving servers what to do if an email fails SPF or DKIM checks, and it provides reporting on these failures. A simple guide to DMARC, SPF, and DKIM can help you get started.
Beyond basic setup, monitor your DMARC reports regularly. These reports provide invaluable insight into who is sending email on behalf of your domain and whether it's passing authentication checks. This helps you identify and mitigate any unauthorized senders or misconfigurations that could contribute to phishing flags.
Optimizing linked login pages and URLs
The login page itself, and how it's linked in your emails, plays a significant role in how Gmail perceives your email's legitimacy. A key requirement is using HTTPS for all login pages. If your login page is not secured with an SSL certificate, it will be flagged as insecure, immediately triggering phishing warnings. Ensure your site's SSL certificate is valid and up to date.
Additionally, avoid using generic or highly simplified login pages that might resemble common phishing templates. Your login page should clearly reflect your brand, with appropriate logos, branding elements, and informative text. It should not just be an input box for a username and password. The domain of the linked login page should also be consistent with your sending domain to avoid suspicion. Fastmail also highlights the dangers of suspicious login pages.
Problematic practices
Non-HTTPS URLs: Linking to http:// sites for login. This is a critical security vulnerability.
Link shorteners: Using URL shorteners that obscure the final destination.
Domain mismatch: Sending from one domain, but linking to a completely different, unrelated domain.
Excessive redirects: Multiple redirections before reaching the final login page.
Recommended approaches
Always use HTTPS: Secure your login page with a valid SSL certificate.
Direct, clear links: Link directly to your branded, official login page.
Consistent domains: Ensure the login page domain matches or is closely related to your sending domain.
Clear branding: Include your company logo and design elements on the login page.
Content and sender reputation best practices
Even with perfect authentication and secure links, your email content can still trigger phishing warnings if it appears suspicious. Gmail's filters analyze various content aspects, including keywords, formatting, and overall message structure. Make sure your email copy is professional, clear, and avoids overly aggressive calls to action or alarmist language often found in phishing attempts.
Maintain a strong sender reputation by consistently sending valuable content to engaged recipients. High bounce rates, spam complaints, and low engagement signals (e.g., emails not opened) can negatively impact your sender score, leading to increased scrutiny and potential phishing flags. Utilizing Google Postmaster Tools can provide valuable insights into your domain and IP reputation, spam rate, and authentication errors, helping you address underlying issues.
Finally, ensure that your 'From' name and email address are clear and recognizable. Avoid using generic or suspicious-looking sender information. Personalization, where appropriate, can also help build trust, but always ensure it's done securely and ethically. Keeping an eye on your deliverability can help you understand why your emails might be going to spam.
Views from the trenches
Best practices
Ensure all login pages linked in emails use HTTPS; this is non-negotiable for trust.
Implement strong email authentication (SPF, DKIM, DMARC) to verify sender identity and prevent spoofing.
Use clear, recognizable sender names and email addresses that align with your brand.
Monitor your domain and IP reputation regularly using tools like Google Postmaster Tools.
Common pitfalls
Linking to non-HTTPS login pages, which immediately triggers security warnings.
Using generic login page designs that mimic common phishing templates.
Including link shorteners or excessive redirects in emails leading to login pages.
Having inconsistent domains between the email sender and the linked login page.
Expert tips
Regularly check your domain’s status on various blocklists (or blacklists), as being listed can severely impact deliverability.
Educate your users about identifying legitimate emails and securing their accounts.
Ensure your email sending volume is consistent, avoiding sudden spikes that can look suspicious to ISPs.
Implement two-factor authentication for your login pages to add an extra layer of security.
Marketer view
Marketer from Email Geeks says that the email structure and whether it contains attachments like PDFs should be reviewed, as these can influence how Gmail perceives the message.
2019-08-29 - Email Geeks
Expert view
Expert from Email Geeks says that compromised linked sites are a common cause of phishing flags, so it is important to ensure all linked domains are secure.
2019-08-29 - Email Geeks
Concluding thoughts on email security
Preventing Gmail from marking your emails as phishing, especially those containing linked login pages, requires a comprehensive approach. It's not just about what you send, but how you send it and where you direct your users. By prioritizing robust email authentication, securing your linked web pages with HTTPS, optimizing the content and branding of your login forms, and maintaining a stellar sender reputation, you can significantly reduce the likelihood of your legitimate emails being flagged.
Consistent vigilance and adherence to best practices for email deliverability are key. Regularly monitor your email performance and address any warnings proactively. This proactive stance ensures that your important communications reach their intended recipients, fostering trust and engagement with your audience.
Gmail can be a frustrating experience, especially when they contain legitimate links to your login pages. It creates a significant hurdle for user experience and can severely impact your email deliverability. This happens because Gmail's sophisticated algorithms are constantly working to protect users from malicious attacks, including various forms of phishing.
Google is very clear about protecting users from phishing, as outlined in their phishing prevention guidelines. If a linked page, especially a login page, doesn't meet their security expectations, it's flagged. You can dive deeper into why emails get a phishing warning in Gmail to understand more.
Gmail perceives your email's legitimacy. A key requirement is using HTTPS for all login pages. If your login page is not secured with an SSL certificate, it will be flagged as insecure, immediately triggering phishing warnings. Ensure your site's SSL certificate is valid and up to date.
Google Postmaster Tools can provide valuable insights into your domain and IP reputation, spam rate, and authentication errors, helping you address underlying issues.
