External links in HTML email preview do not open in the default browser

[projecthanif]

Bug description

Clicking a button or hyperlink inside an email's rendered HTML preview does nothing. NativeMailer does not open the target URL in the system's default browser.

Steps to reproduce

1. Launch NativeMailer on macOS.
2. Open an email that contains a button or hyperlink.
3. View the email in the HTML tab.
4. Click the button, for example Review testimonial, or click the fallback URL below it.

Expected behavior

The target URL should open outside NativeMailer in the user's default web browser.

Actual behavior

The click does not open the browser or navigate to the target URL.

Environment

• OS: macOS
• App: NativeMailer desktop application
• Preview tab: HTML

Additional context

This affects both styled buttons and normal anchor links rendered inside the email preview. The preview likely needs to intercept external link navigation and hand it off to the operating system's browser.