The information below was borrowed from this website https://owl.purdue.edu/owl/general_writing/academic_writing/email_etiquette.html

This website has all kinds of information for presenting professional writing, scholarly presentations and other helpful "how to's" for your future life in interior design.

Email Etiquette

How do I compose an email to someone I don't know? AKA how to write an email to your instructors, guidance counselors, school staff?

There are a few important points to remember when composing email, particularly when the email's recipient is a superior and/or someone who does not know you.

Be sure to include a meaningful subject line; this helps clarify what your message is about and may also help the recipient prioritize reading your email
Just like a written letter, be sure to open your email with a greeting like Dear Dr. Jones, or Ms. Smith:
Use standard spelling, punctuation, and capitalization. THERE'S NOTHING WORSE THAN AN EMAIL SCREAMING A MESSAGE IN ALL CAPS. Do not use text abbreviations (like u instead of you, for example).
Write clear, short paragraphs and be direct and to the point; professionals and academics alike see their email accounts as business. Don't write unnecessarily long emails or otherwise waste the recipient's time.
Be friendly and cordial, but don't try to joke around (jokes and witty remarks may be inappropriate and, more commonly, may not come off appropriately in email)
Make sure to include a signature block that contains the necessary information for someone to reach you should a reply be necessary and/or expected; typical closings include a sign off phrase (e.g. best, thanks, sincerely) and the sender's name. Additional information may be included when appropriate (e.g., department, office location, position, etc).

What are some guidelines for continuing email conversations?

Once you have exchanged emails with a person on a given subject, it is probably acceptable to leave greetings out of your follow-up emails. Here are some other points to consider about continuing conversations over email:

Try to respond within a reasonable time frame, though "reasonable" will depend on the recipient's expectations and the subject being discussed
Trim back the old messages: most email clients will keep copying older messages to the bottom of an email. Delete older messages so as to keep your message size from getting too large, and to keep your messages looking clean.
If someone asks a lot of questions, it may be OK to embed your answers into the sender's message copied at the bottom of your email. However, if you're going to do this, be sure to say so at the top, and leave generous space, for example:
> How long are you staying?
Less than two weeks.
>Will you have time to visit with us?
I'm really hoping to, but my schedule will be pretty tight. Let me get back to you about that after the weekend.

What sorts of information shouldn't be sent via email?

Most people do not realize that email is not as private as it may seem. Without additional setup, email is not encrypted; meaning that your email is "open" and could possibly be read by an unintended person as it is transmitted to your reader. With that in mind, never send the following information over email:

Usernames and passwords
Credit card or other account information

Additionally, avoid sensitive or information that could be potentially damaging to someone's career and/or reputation, including your own. Beyond email's general lack of security and confidentiality, your recipient can always accidentally hit the Forward button, leave their email account open on a computer, or print and forget that they've printed a copy of your email.

What about sending attachments?

Here are some guidelines you should follow:

Never send an attachment to someone you don't know the first time you contact them (unless, of course, the contact has posted a job ad requesting a resume in a Word document). They (or their computers) might think it is spam or a virus, and delete your message.
Avoid unnecessarily large file sizes, digital photos especially. Most digital photos come off the camera much larger than can be viewed on screen. Learn how to resize your digital photo files.
When you must send a large file or set of files, do the recipient the courtesy of sending an email telling them what you'll be sending and why.
Be sure to have anti-virus software installed on your computer to scan all of your outgoing and incoming messages for viruses.