How does including email addresses in URL links affect deliverability at Gmail?
Michael Ko
Co-founder & CEO, Suped
Published 4 Aug 2025
Updated 17 Aug 2025
7 min read
Email deliverability is a complex landscape, constantly evolving with new spam filtering techniques and sender requirements from major inbox providers like Google. One area that often causes confusion is the impact of including email addresses directly within URL links in your emails. While it might seem like a convenient way to pass user-specific data, this practice can significantly hinder your email's ability to reach the inbox, particularly with Gmail.
The core issue revolves around security, privacy, and how mailbox providers (MBPs) interpret such links. When an email address is embedded directly into a URL, especially as a query parameter (e.g., example.com/?email=user@example.com), it raises multiple red flags. This approach is often considered a bad practice due to the potential for exposing personally identifiable information (PII).
This article will explore why including email addresses in URL links affects deliverability at Gmail, touching on the privacy concerns, security risks, and how Google's sophisticated spam filters perceive such links, potentially leading your legitimate emails straight to the spam folder.
Why it's perceived as suspicious
Gmail's primary concern is protecting its users from phishing attempts and ensuring a secure email environment. When an email address is visible in a URL, even if it's a legitimate user ID, Gmail's filters (and those of other major providers) can interpret this as a potential security vulnerability. This is because email addresses are often targeted in phishing scams, and their presence in URLs can mimic malicious attempts to trick users into revealing sensitive information.
The system sees the pattern of an email address within a web link and flags it as suspicious. This isn't necessarily about the link being inherently broken or leading to a dangerous site, but rather the structural format itself triggering a cautionary response. It's a proactive measure to safeguard users against fraudulent activities, even if it sometimes affects legitimate senders. You can read more about how hyperlinks in the body affect deliverability.
The risk
Including PII like email addresses in URLs increases the risk of your emails being marked as spam or even triggering phishing warnings within Gmail. This directly impacts your sender reputation, making it harder to reach the inbox for all your future campaigns. It's perceived as a privacy breach and security vulnerability.
Beyond deliverability, exposing PII in URLs can lead to compliance issues, especially with regulations like GDPR in the EU. Fines for such violations can be substantial.
While Google's official documentation for email deliverability might not explicitly state, "do not put email addresses in URLs," their broader policies on handling PII across their platforms (like Google Ads and Analytics) strongly advise against it. These policies reflect a general stance on data privacy and security that extends to their email filtering practices. If Google's ad platforms flag PII in URLs, it's reasonable to assume their email systems would apply similar scrutiny.
Impact on sender and domain reputation
A key factor in email deliverability is your sender and domain reputation. Gmail, like other mailbox providers, assesses the trustworthiness of senders based on various signals, including the content of your emails and the links they contain. When email addresses appear in URLs, it can negatively impact this reputation.
Spam filters (or blocklists) are designed to identify and quarantine messages that exhibit characteristics common in spam or phishing attempts. Including PII in URLs is one such characteristic that can trigger these filters, leading to your emails landing in the spam folder instead of the primary inbox. This can affect your overall email deliverability rates, even for otherwise healthy sending practices. You can always check if you're on a blocklist.
Direct impact on deliverability
Spam classification: Links with embedded email addresses are more likely to be flagged by Gmail's filters and routed to the spam folder. This can also happen if you are using URL shorteners that have a poor reputation.
Phishing warnings: Gmail may display warnings to recipients, indicating that the link could be suspicious or a phishing attempt, severely reducing trust and engagement.
Domain reputation: Consistent use of such links can degrade your sender and domain reputation with Gmail, affecting all your email campaigns.
Indirect impacts
Reduced engagement: When emails land in spam or show warnings, recipients are less likely to open, click, or engage with your content, hurting your overall email marketing performance.
Compliance risks: Depending on your audience's location, exposing PII in URLs can violate data privacy regulations like GDPR or CCPA, leading to severe penalties. For more details, see our guide on risks of including email addresses as URL parameters.
Brand perception: Repeated issues can damage your brand's image, making recipients distrust your communications and potentially leading to unsubscribes or spam complaints.
Even if the link is otherwise valid and points to your own domain, the inclusion of an email address is a historical signal for suspicious activity that modern filters are trained to detect. This makes it a significant, albeit often overlooked, factor in email deliverability issues.
Safer alternatives for tracking and personalization
Instead of embedding email addresses directly into URLs, there are safer and more deliverability-friendly ways to pass user-specific data or track engagement. Using unique, randomized identifiers or tokens is a much better approach. These tokens can be generated and linked to specific users in your database without exposing their email address in the URL itself.
Another effective method is to use server-side session management or cookies once the user lands on your website. After a user clicks a generic, clean link, your website can handle the authentication or personalization based on their session, securely. This eliminates the need to transmit sensitive PII via the URL, making your links cleaner and less prone to triggering spam filters.
For email authentication or one-click login links, a similar token-based approach is standard. The token is temporary and single-use, providing a secure way to verify the user without exposing their email address in the URL. If you need to include an email address in a URL, consider mailto links for their intended purpose only.
Best practices for link usage
Maintaining a strong email deliverability is crucial for any successful email program. While the exact algorithms used by Gmail's spam filters are proprietary, their stance on PII and security is clear across all their platforms. Avoiding the inclusion of email addresses in URL links is a fundamental best practice that contributes to healthier email deliverability.
Adopting secure methods like token-based URLs or server-side data handling not only improves your inbox placement but also demonstrates a commitment to user privacy and data security. This builds trust with both your recipients and mailbox providers, leading to better long-term email performance. Furthermore, be mindful of how many links are included.
Regularly monitoring your domain health with Google Postmaster Tools can provide insights into how your links are perceived and help you identify and rectify any issues proactively. Prioritizing user safety and privacy in your email practices will always lead to better deliverability outcomes.
Views from the trenches
Best practices
Always prioritize user privacy by avoiding PII, like email addresses, in your email URLs.
Utilize token-based authentication or server-side data handling for personalization and tracking to ensure secure data transfer.
Regularly monitor your email sending reputation using tools like Google Postmaster Tools to catch any potential issues early on.
Ensure all links in your emails are secure (HTTPS) and lead to reputable domains to maintain trust with inbox providers.
Educate your team and clients about the deliverability and compliance risks associated with PII in URLs.
Common pitfalls
Directly embedding recipient email addresses into URL query parameters.
Ignoring Google's broader PII policies and assuming they only apply to Ads or Analytics.
Using URL shorteners or third-party links with poor reputations.
Failing to implement proper authentication (SPF, DKIM, DMARC) alongside clean link practices.
Disregarding GDPR or other data privacy regulations when sending to EU recipients.
Expert tips
Implement robust DMARC policies to protect your domain from impersonation, which often involves malicious links.
Segment your audience and personalize content without resorting to PII in URLs.
Conduct A/B tests on email content and link structures to understand their impact on deliverability.
Engage in active list hygiene to remove inactive or invalid email addresses, improving overall sender reputation.
Stay informed about updates to email sending guidelines from major mailbox providers.
Expert view
Expert from Email Geeks says that embedding email addresses in links for deliverability has been a concern for a very long time, possibly dating back to pre-2004 for providers like Microsoft. It is a very bad practice regardless of its direct effect on deliverability because of security implications.
2024-10-24 - Email Geeks
Marketer view
Marketer from Email Geeks reports seeing recent issues where links containing what looked like recipient email addresses were rewritten or broken by consumer mailbox providers, indicating this is still an active concern.
2024-09-15 - Email Geeks
Final thoughts on secure linking
In conclusion, while there might not be a single, publicly available Gmail guideline stating, "Do not include email addresses in URL links," the evidence from Google's broader PII policies, combined with the observed behavior of spam filters and the fundamental principles of email security, strongly advises against this practice. It's an unnecessary risk that can compromise your deliverability and your brand's reputation.
Prioritizing the security and privacy of your recipients should always be paramount. By adopting secure methods for personalization and tracking, you not only improve your inbox placement rates but also build a more trustworthy relationship with your audience and mailbox providers. This proactive approach ensures your emails consistently reach their intended destination without triggering alarms.
Staying informed about email best practices and adapting your sending strategies to align with the evolving landscape of email security is key to long-term success. Always err on the side of caution when it comes to user data in URLs to maintain optimal deliverability.
