When requesting PTO in an email, it is crucial to include a clear subject line, use a professional greeting, and provide detailed information about your request for paid vacation days. The subject line should be concise and informative, the greeting should be appropriate for the recipient, and the request should be clear and honest. Additionally, demonstrating preparations and asking for permission in a respectful manner can increase the likelihood of approval. Finally, close the email with a conclusion paragraph and a professional sign-off.