Don't send offensive, obscene or abusive e-mail messages to other people.
Don't send unsolicited e-mail to anybody.
Don't send or forward junk e-mail or chain mails; the only sensible thing to do with a chain or junk mail that you receive is to delete it immediately. Note: that virtually all virus warning messages are hoaxes and should not be forwarded.
Housekeeping
Check your mail regularly; there is nothing more frustrating than waiting for a reply on a urgent message.
Always
reply to genuine e-mail messages, even if a brief acknowledgment is all
you can manage, no response can create doubt in the mind of the sender
that you ever received it. On the other hand, never reply to junk e-mail.
Reply promptly; it is easy to forget an e-mail message if you don't deal with it immediately.
Delete
all unwanted messages and messages that have been dealt with; this will
make you mailbox easier to manage and will conserve disk space.
Develop an orderly filing system for those e-mail messages you wish to keep, store messages in folders.
Composing messages
Try to keep e-mail messages brief.
Make sure that the Subject field of your e-mail message is meaningful.
Be
very careful how you express yourself; especially if you feel heated
about a subject. E-mail lacks the other cues and clues that convey the
sense in which what you say is to be taken, and you can easily convey
the wrong impression.
Keep sentences and paragraphs short; try
to be as concise as possible without losing the meaning of what you
wish to put across. Separating paragraphs with a blank line makes them
easier to read.
If you mean something in jest, use a "smiley" :-) to convey that.
Don't write in all upper case; it is considered as SHOUTING, and is harder to read.
Include some form of salutation; including 'Dear So-and-so' is not only friendly but helpful if you message is copied to others.
Always re-read messages before sending them to check that they say what you intended.
Avoid abbreviations, acronyms and 'xt speak' as these can easily be misunderstood.
Forwarding
Please
use the BCC field when forwarding messages or when sending to multiple
recipients; you might inadvertantly be giving your and your friends'
email addresses to spammers if you don't use the BCC field.
Setup your email application to not add characters like '>' to the original message.