When copying HTML code from Microsoft Edge's code viewer (DevTools) and pasting it into an Outlook email as inline text, Outlook becomes unresponsive for 10–15 seconds. This triggers a “Close or Wait” dialog, which appears to be a crash but is actually a rendering delay. The same HTML, when copied from Firefox DevTools or Notepad++, does not cause this issue. This suggests that Edge includes clipboard metadata (e.g., text/html) that causes Outlook to treat the content as active HTML, attempting to render it — including <style> blocks and @font-face rules — which overwhelms the Word-based rendering engine. Steps to reproduce: Open a large HTML file with embedded <style> and @font-face blocks in Edge. Copy the code from Edge DevTools or a code viewer. Paste it into an Outlook email body (not as an attachment). Attempt to view the sent email or open it in the Sent folder. Expected behavior: Outlook should treat the pasted content as plain text or render it safely. Actual behavior: Outlook freezes for several seconds, prompting a crash dialog. Workaround: Copying the same content from Firefox or Notepad++ avoids the issue. Suggested fix: Strip or sanitize clipboard metadata from Edge DevTools when copying code, or improve Outlook’s handling of complex inline HTML with metadata.