How to do it properly.

Email works a lot better when people use it properly. There are standards for how you use email - it's not just a personal choice as to how you set it out. Keep in mind that email is read by a computer (usually several, in fact) as well as a person.

If you're looking for concrete, definitve and authoritative standards, check out:

Note: An RFC is a particular type of document relating to Internet standards. It must be approved by the RFC editor of the Internet Engineering Task Force - see their website for more information. The IETF is an internet standards organisation.

Unless messages are encrypted and/or signed, mail is an insecure medium. Anyone may place a letter in your snailmailmailbox with whatever they write as the return address; anyone may do the same with an email.

Faking a "From: " address is easy. Do not assume a message is genuine.

If you require a secure medium, use GPG or PGP encryption and signing on your mail. Signing a message allows the recipient to check that the author of a message is who they say they are and the message content has not been tampered with. Encryption protects the content of the message from being seen.

My gpg key is available from my contact page.

One drawback of PGP/GPG encyption and signing is that they only protect the message content, not the headers. The Subject and To headers can be changed easily, which may change the aparrent meaning of the mail - for example, a message informing a employee of a raise could be altered to look like it went to a different employee, even though the message was signed. To avoid this problem, include the information in the To and Subject headers in the mainh message.

These might seem like trivial things or personal preferences, but mail is examined by computers, and they assume things are done as defined in the standards. Not following the standards makes it much more likely that you message will be marked as spam and bounced or deleted.

Email is a plain text medium. Your message is transmitted in plain text with anything else as an attachment. An HTML-only email is not a valid email message.
Line breaks must be inserted at less than the standard terminal size (less than 80 characters). Preferably at around 72 characters.
A ">" character and a space should be used to offset quoted text in replies. Replies should be rewrapped if necessary (i.e. they go over the 80/72/60 character limit).
A reply must be typed below quoted text. If it is neccessary to seperate points or paragraphs in the original text this is acceptable, as long as you type the reply to that "section" of the original text below the relevant section. This allows mail to be read top-to-bottom and it makes a hell of a lot more sense when you are reading it 5 months later.
Do NOT include binary data and/or attatchments larger than 100KB unless the reciever has specifically requested them. If neccessary, ask if they want the file; alternatively place it on a file server - even your webspace - and mail them information telling them how to access it.
Always place your signature with a single line containing "-- " before it. There should be a single space after the two dashes.

Coming soon.