What sort of email etiquette are you aware of, especially when addressing your instructors?

When/why email was invented (discussed in the textbook) ? How it may have changed over the years? Do people use email more/less often now to communicate?

When do you use e-mail?

What can you say over e-mail that you wouldn’t say in person? Where’s the dividing line?

What sort of email etiquette are you aware of, especially when addressing your instructors?