how to whitelist a webpage in mimecast

Everly

2 min read

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17-01-2025

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Mimecast is a powerful email security solution, but its aggressive filtering can sometimes block legitimate websites. If you're having trouble accessing a specific webpage due to Mimecast's security measures, you'll need to whitelist it. This article provides a step-by-step guide on how to whitelist a webpage in Mimecast, ensuring seamless access for you and your users.

Understanding Mimecast's Web Security

Before we delve into the whitelisting process, it's crucial to understand why Mimecast might block a website. Mimecast employs various techniques to protect against phishing, malware, and other online threats. These techniques include URL filtering, which checks websites against known malicious domains and suspicious content. Sometimes, however, legitimate websites can get caught in the net.

This often happens with:

• New websites: Newly launched sites might not yet be indexed by Mimecast's threat databases.
• Dynamic URLs: Websites that use dynamic URLs (those containing variables) might be flagged as suspicious.
• False positives: Mimecast's filtering system, like any system, isn't perfect and can occasionally produce false positives.

How to Whitelist a Webpage in Mimecast: A Step-by-Step Guide

The precise method for whitelisting a webpage depends on your Mimecast setup and the specific features enabled. However, the general principles remain consistent. Here's a common approach:

1. Identify the Exact URL: This is the most critical step. Make sure you have the complete and accurate URL of the webpage you want to whitelist. Include the "https://" or "http://" prefix. Inaccuracies will lead to failure.

2. Access the Mimecast Admin Console: Log into your Mimecast admin console using your administrator credentials. The exact URL will depend on your Mimecast deployment.

3. Navigate to the Web Security Settings: The location of web security settings varies slightly across Mimecast versions. Typically, you'll find this under sections like "Security," "Policies," or "Web Security." Look for options related to URL filtering or web security policies.

4. Locate the Whitelisting Feature: Once in the web security settings, look for a section dedicated to whitelisting or exception handling. This might be labeled as "Allow List," "Whitelist," "Exceptions," or something similar.

5. Add the Webpage URL: In the whitelisting section, you'll usually find a field or interface to add URLs. Enter the complete URL you identified in Step 1. Be mindful of wildcards. Using them too broadly might open security vulnerabilities.

6. Save the Changes: Once you've added the URL, save your changes. This usually involves clicking a "Save," "Apply," or "Submit" button.

7. Verify the Whitelisting: After saving, test the whitelisting by attempting to access the webpage again. If it still blocks, double-check your URL, verify your changes were saved correctly, and contact Mimecast support.

Troubleshooting and Best Practices

• Contact Mimecast Support: If you encounter difficulties whitelisting a webpage, don't hesitate to contact Mimecast support. They have the expertise to diagnose and resolve issues.

• Use Specific URLs: Avoid using wildcards (*) unless absolutely necessary. Overly broad whitelisting rules can compromise security.

• Regularly Review Your Whitelist: Periodically review your whitelisted URLs to ensure they remain legitimate and necessary. Remove any outdated or unnecessary entries.

• Consider Alternative Solutions: If whitelisting isn't feasible or desirable, explore alternative solutions such as adjusting your Mimecast security policy or creating specific exceptions for your users.

By following these steps, you can effectively whitelist webpages in Mimecast, ensuring your users can access legitimate websites while maintaining a strong security posture. Remember to always prioritize security and exercise caution when adjusting security settings.