Here are the parts of the email that you should include when reaching out to a professor. Before emailing them, try your best to answer as many of your questions as possible by reaching out to other students, TAs, reading the syllabus, or attending a MASH session.
Start the email with "Dear" or "Hello."
The Title and Name
Then follow up with the professor's title and name. Most professors will be addressed by "Professor" or "Doctor." If you are not sure which one to use, it is always better to be too formal than not formal enough.
Professors have a lot of students and can teach multiple classes, so provide some context about yourself and what class you're reaching out about. Provide a specific class name or section of the syllabus.
Keep it Short
Professors are busy people and will most likely avoid long emails. Keep things short and concise to get the point across without having to send multiple emails.
End the email with a "Thanks" or "Best" followed by your name.
Use a Clear Subject Line
The subject line should reflect what your email is about.
Use Your School Email
Always email your professor from your university email address so they know you are one of their students and the professional relationship is established.