The easiest email to write is one intended for a friend. You have a relationship with this person and therefore most likely have a communication style between the two of you. Unlike colleague to colleague or client to client emails, friend to friend emails are much more informal. There are few guidelines to follow, only proper etiquette that even most friends won't hold you to or judge you on.
Write a short phrase in the subject line. The subject must clearly relay the reason for your email.
Start your email with a casual greeting such as "hello, "hi there" or "what's up?"
Ask your friend questions about his life. Be specific. Ask him about certain people, jobs or circumstances currently in his life. If you haven't spoken to one another in a while, ask in general terms about these topics.
Advise your friend of what's happening in your life. You can write about important people in your life, jobs, school or other subjects close to your heart. Be sincere.
Suggest that the two of you get together for coffee or lunch in the near future. Let her know what times work best for your schedule and ask that she respond with times that work for her.
Close your email with "hope to see you soon,""love" or "talk soon" followed by your name.
Hit the "Send" button and wait for his response.
When you write to a friend or acquaintance, it's acceptable to use smiley faces or any other fun text styles and emoticons.
Avoid writing "hi" or "hello" in the subject line because some service providers automatically put these emails into your "Spam" or "Junk" folders. Use language that can't get misinterpreted. Often times people read things differently. If you have any doubts that your message might not be clear, pick up the phone and call that person instead.