Choose an email object

For example this pattern is great: [Action] Topic. Action to help your recipient to understand what you want from him. topic is a small synthesis of the topic in which the action is supposed to happen. This pattern has been advised by Michael Kahn.

Keep the body narrow

The email should not size more than 72 character width. This improve readability specially on small screen. In vim, the width can be setup, and the shorkey g+q on a visual selection makes things easy.

Reply below your recipient

Bottom Posting (BP) is answering bellow the previous email as opposite to Top Posting (TP) aka gmail way of doing. BP has many advantages over TP. BP allows to read the emails in the natural order ; specially for people who discover the thread. more information here Keep an empty row between the previous answer and yours for readability.

Remove information

Remove the recipient signature, out of context content. In particular, do not keep the recipient email within the email body for security reasons.

Append your signature

A signature is generally on the bottom of the email, preceded by a row containing: --

Sign the email

Sign the email with your AES private key as a proof of your identity.

Mask your mailing system

Email can store the User-agent field. This can be found in the header of the email and may share precious information such your operating system and its version. eg: User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0

Email the mailing list only

Remove the previous writer. In any cases, he will receive the email since he subscribed to the list.

Use a dedicated alias

Mailing list are usually public and this you will probably end up with spam. A good trick is to use an alias combined with a rule such: "message directed to the alias goes into the trash". Riseup.net provides alias email.