Why does the Outlook app display the URL behind href links in the email content?
Michael Ko
Co-founder & CEO, Suped
Published 17 Apr 2025
Updated 17 Aug 2025
9 min read
Occasionally, email marketers and deliverability professionals encounter a peculiar behavior in the Outlook app where the full URL behind an href link is displayed directly in the email content, instead of just the anchor text. This can be confusing, as it often appears inconsistent across different emails and recipients. I've heard of situations where recipients report seeing this only for specific emails, leading to concerns about broken email formatting or even phishing attempts.
This behavior isn't necessarily a bug in your email's HTML, but rather a result of how Outlook, particularly the mobile app, processes and renders links, often influenced by security features. Understanding these mechanisms is key to diagnosing and potentially mitigating why an Outlook app might display the raw URL, impacting how your email content is perceived and delivered. It's important to differentiate this from common email click tracking or email filters modifying links.
Outlook's link processing and security features
Outlook's email client, especially the app version, employs various strategies to enhance security and user experience. One prominent feature is Safe Links, part of Microsoft Defender for Office 365, which is designed to protect users from malicious URLs. When an email contains links, Safe Links technology actively scans and rewrites them. This process helps safeguard against phishing attacks and other scams by redirecting clicks through Microsoft's security scanners before reaching the destination. For more details, learn more about Safe Links.
While this rewriting is typically seamless, sometimes the mechanism might lead to the full, rewritten URL being displayed alongside, or even instead of, the original anchor text. This is often an attempt by the client to show the user the ultimate destination of the link, especially if it suspects any discrepancy between the displayed text and the underlying URL. This behavior can be particularly noticeable with certain tracking links or if the email's HTML structure for links is atypical.
Understanding how Microsoft 365 filters emails based on URL reputation is crucial. The client's decision to display the raw URL can also be influenced by how it perceives the link's trustworthiness. If the URL or the sending domain has a questionable reputation, Outlook might be more inclined to reveal the full path as a warning sign to the recipient. This is an extra layer of security intended to make users aware of where they are truly navigating.
It's a delicate balance between providing a clean user experience and ensuring security. For more general information on how Outlook handles links, Microsoft provides a comprehensive guide to understanding links in email messages.
Causes for raw URL display
While security features are a primary reason, other factors can contribute to the Outlook app displaying raw URLs. One common cause is HTML coding issues within the email itself. Inconsistent or malformed HTML for hyperlinks can sometimes confuse email clients, leading them to fall back to displaying the raw URL instead of correctly rendering the anchor text.
Email Service Providers (ESPs) often implement their own link tracking mechanisms to gather data on clicks. This involves wrapping original URLs in a tracking URL. While this is standard practice and usually goes unnoticed by the recipient, in some cases, particularly with specific Outlook app versions or complex tracking setups, the app might render this tracking URL explicitly. This is not necessarily a bug, but rather an unintended rendering outcome due to how the app interprets the nested or redirected link structure.
Furthermore, Outlook's rendering engine (or the rendering behavior of specific versions, especially on mobile platforms like Android) has unique quirks. Unlike web browsers that typically handle HTML consistently, email clients often interpret CSS and HTML differently. This can lead to unexpected display issues, including links. Sometimes, if the email contains a link in the first few lines, Outlook may choose to display the URL instead of the preview text, as a feature. This behavior is sometimes specific to certain email clients or apps and not always consistent across all emails, even from the same sender.
It’s important to remember that email rendering can be highly variable depending on the recipient's client, operating system, and even their personal settings. What looks perfect in one environment might have minor (or major) rendering discrepancies in another. This is why extensive testing across different email clients, including various Outlook versions, is always recommended before sending out campaigns.
Impact on user experience and deliverability
When the Outlook app displays the raw URL, it can impact both user experience and, indirectly, email deliverability. From a user's perspective, seeing a full, long URL, especially a tracking URL, can look unprofessional or even suspicious. Recipients might hesitate to click on such links, fearing that they are not legitimate or could lead to malicious websites, even if the content is completely harmless. This can lead to reduced click-through rates and engagement for your campaigns.
More critically, this visual discrepancy might contribute to a perception of your emails as less trustworthy. If recipients consistently see unexpected URLs, they might start flagging your emails as spam or phishing, even if your sender reputation is otherwise strong. This could potentially increase spam complaints or decrease positive engagement metrics, which email providers (including Outlook) use to assess your sender reputation. A poor reputation could then lead to more emails landing in the spam folder or being blocked entirely.
While the direct impact on deliverability is often minimal for a single instance, a recurring pattern of raw URL display can indirectly affect your sender metrics. Mailbox providers prioritize a positive user experience. If their users are consistently seeing what they perceive as messy or suspicious links, it can reflect poorly on the sender. This is why it's important to monitor how your emails are rendered across different clients.
Addressing this issue proactively can help maintain a strong sender reputation and ensure that your messages are not only delivered but also well-received. Ignoring such rendering quirks can lead to a gradual erosion of trust and engagement, ultimately hindering the effectiveness of your email marketing efforts. This is a subtle yet significant aspect of email deliverability.
Preventative measures and troubleshooting
To minimize the chances of Outlook displaying raw URLs, consider the following preventative measures and troubleshooting steps. Ensuring your email's HTML is clean and robust is a good starting point. This means using valid, well-formed HTML for your links, avoiding overly complex nested structures where possible, and adhering to email coding best practices.
For Outlook's specific rendering quirks, particularly on mobile, extensive testing is indispensable. Use email preview tools that simulate rendering across various clients and devices, including different versions of the Outlook app (e.g., Android, iOS, desktop). This allows you to identify and address issues before your emails reach recipients.
If you suspect an ESP's link tracking is contributing to the issue, investigate their documentation for how links are handled. Some ESPs offer options to customize link tracking behavior or provide cleaner, less intrusive tracking URLs. You might also want to review your overall email authentication setup, including DMARC, SPF, and DKIM. Strong authentication can build trust with mailbox providers, potentially reducing the likelihood of their security features (like Safe Links) triggering explicit URL displays.
Finally, maintaining a good sending reputation is always paramount. Avoid sending emails that trigger spam traps, monitor your blocklist (or blacklist) status, and ensure your email content is relevant and engaging. A positive sender reputation can influence how lenient mailbox providers are with rendering quirks, ensuring your emails are delivered and displayed as intended.
Views from the trenches
Best practices
Maintain clean HTML for links, avoiding complex nested structures.
Use reputable Email Service Providers that handle link tracking gracefully.
Regularly test email rendering across various Outlook clients, especially mobile versions.
Implement and maintain strong email authentication protocols like DMARC, SPF, and DKIM.
Monitor your sender reputation and avoid practices that lead to spam complaints.
Common pitfalls
Relying solely on desktop Outlook previews, neglecting mobile app rendering differences.
Ignoring subtle link display inconsistencies, assuming they are harmless.
Over-complicating HTML for links, leading to parsing issues by email clients.
Failing to understand how ESPs modify links for tracking purposes.
Not considering that recipient security settings can alter how links are displayed.
Expert tips
Check the raw email source to see how the links are truly structured before rendering.
Ensure the `href` attribute is always present and correctly formatted in your HTML.
Consider if the displayed URL is part of a URL shortening or tracking service.
Review any custom CSS affecting link appearance or behavior in Outlook.
Educate your recipients that some display changes are security features, not errors.
Marketer view
Marketer from Email Geeks says they would initially suspect an HTML coding bug in the email template.
2023-11-21 - Email Geeks
Marketer view
Marketer from Email Geeks says they looked at the visible URL and thought it might be an ESP adding its link tracking into the email code incorrectly.
2023-11-21 - Email Geeks
Ensuring optimal link display in Outlook
The display of raw URLs in the Outlook app can be a perplexing issue for email senders, often stemming from a combination of the app's security features, particularly Safe Links, and nuances in email HTML rendering. While designed to protect recipients, these features can sometimes lead to unexpected visual outcomes, impacting the perceived professionalism and trustworthiness of your emails. It's crucial for senders to understand that this isn't always a sign of faulty HTML but rather a client-side interpretation.
To ensure your emails render optimally and build recipient trust, prioritize clean HTML, conduct thorough testing across various Outlook environments, and maintain a robust email authentication and sender reputation strategy. By proactively addressing these factors, you can minimize unintended link displays and ensure your messages are consistently delivered and presented as intended, safeguarding both user experience and your long-term deliverability.
Outlook app where the full URL behind an href link is displayed directly in the email content, instead of just the anchor text. This can be confusing, as it often appears inconsistent across different emails and recipients. I've heard of situations where recipients report seeing this only for specific emails, leading to concerns about broken email formatting or even phishing attempts.
Outlook) use to assess your sender reputation. A poor reputation could then lead to more emails landing in the spam folder or being blocked entirely.
