Always be aware that email is never confidential. Anything in an email can be seen by others with the right tools and access. Think of email as a postcard. Don’t send things to people unless you are really quite certain they would like to receive it.
If you are attaching something to an email, and the recipient is not expecting it, send a separate email telling them that you are doing so and that it is intended.
Always include the original email in your reply, so that the recipient will understand the context of your response.
Open and respond to email promptly – daily is a minimum. If you are not going to use email at least daily, please do not use it at all.
Always include a Subject that gives a hint of what the email is about.
Use BCC (Blind Carbon Copy), to protect your friends. Only use CC if it is important that the recipients know who else got it.
Consider the Internet speed available to your recipient when thinking about an attachment. A large picture, video or tune of 5 megabytes could take 10 minutes to receive if their service is a low-speed one, and their service may not even allow attachments greater than 5 megabytes.
Do not use all upper case letters. This kind of email feels like you are yelling.
Take the time to compose something that is readable, interesting and concise. Choose your words wisely. It is easy to unintentionally cause a reader to misinterpret your meaning, when using email or texting.
Do not even consider attaching application programs.
Consider carefully before using Reply All.