I’m guessing that about 3% of the people I correspond with via email will actually read this, but here goes anyway.
Here is a short list of things that I ask of people who email me:
Please do not top-post.
(This means please don’t write your reply above the quoted text of the message to which you are replying).
When you top-post, you are telling me that you would rather that I spend my time to figure out what part of the original message you are replying to, than spend the time yourself to edit your message and make your meaning clear. People read top-to-bottom. Don’t make me read bottom-to-top to figure out what you are trying to tell me.
(See http://idallen.com/topposting.html. Also, I will be reasonably tolerant when the sending mail UA makes bottom-posting difficult, e.g. UAs that do not >-indent quote messages. Users replying on mobile devices have a bit more leeway, since bottom-posting on such devices can be incredibly frustrating, or simply impossible.)
Please do not attach Word documents.
I have to accept such attachments at work, where this is all we use. I do not have to accept such attachments in personal correspondence. The first time I am sent a Word document by somebody I will reply and request that the next time they send me a document the use a standard format like PDF. From then on I will discard Word documents that I am sent.
Please use a sane auto-responder configuration.
If you use a vacation or out-of-the-office auto-responder, please configure it to reply to the same person no more than once a day. I don’t have a great memory, but I don’t need to be told twice in 10 minutes just because I need to correct something in the last message to you.