You would never walk into a room, and start talking to someone without at least saying hello. But many people start e-mails without any introduction. They also end without saying goodbye.

Here are some good and bad introductions:

Hello,
Hi,
Peter,

Hi Jane,
Dear Ben,
 (a bit formal)

Hello Mr Smith,
(too formal, unless they are a customer/client)
What's up,
(too informal)
Good Morning,
(you don't know what time they will check their mail)

If you are wondering how formal you should be, there are a couple of tricks you can use.

Firstly, if you are replying to an e-mail they sent you, just echo back their opener. If they write "Hi Harry," you can start your response with, "Hi Mike,"

Secondly, if you have never written to them before, go for the default "Hello <name>," as this is neither too formal or informal.

Generally, you should always use a more formal opener in a work environment that you would with friends.

 

As for saying goodbye, there are numerous ways you can do this. Just make sure you give your name - which should appear on the second line after your close.

If you are in frequent communication with the receiver, your first name will probably do. If you don't know them too well, or if this is your first communication, use your full name.

Kind regards,
Peter

Thanks,
Tony Jones
Thanks, Tony
(put on separate lines)

Yours eternally,
Jonathon
(if you want to express your undying love for them, send them some flowers instead)