What is the proper way to address and format an email to a teacher?

When addressing a teacher in an email, use their title (e.g., Mr., Mrs., Dr.) followed by their last name. In the email subject line, include a clear and concise summary of the message. Begin the email with a formal greeting, such as "Dear Mr. Smith," and end with a polite closing, like "Sincerely" or "Best regards." Be sure to use proper grammar, punctuation, and a professional tone throughout the email.