When I was young, we were taught in class how to write different types of letters like friendly and business letters. I knew the convention of writing the word "dear" plus the name of the recipient: Dear Mary, I also know that aside from "dear", there are many other words that can be used like "hi": Hi Peter, I know that the word "dear" is synonymous to "love" so I thought that when you write "Dear Mary", it might be interpreted as you are affectionate with Mary, esp. if she is not a relative like a cousin, aunt, or grandmother. In order to avoid being teased, I simply wrote the name of the recipient when writing letters: Mary, Peter, But my teacher discouraged me saying that it was impolite not to use "dear" when writing letters. Years later, I thought that she might be wrong as it might not be necessarily impolite. Maybe using "dear" is just a convention in writing letters and it doesn't really mean anything. So I always used either "dear" or "hi" since then. Do you agree that it is impolite when you omit "dear" or "hi" and simply write the name of the recipient plus a comma?