Here are a few suggestions for sending e-mail—to anyone, not just to me.
If you are having difficulty reaching me, you may want to know how to get past my spam filter.
Notify before sending large messages. It's a good idea to check before sending someone a large file. He (or his ISP) may have a size limit, and his connection may be over a slow dialup line.
I used to have a limit of 200 KB back when I was on a 56 kb/s dialup line. My current limit is 5 MB.
Don't send useless attachments. It's also a good idea to check whether your recipients can open or use the word-processor document or cute Santa program you want to send them. A Mac or Linux user is not going to be able to run a .exe file, and will be able to read a Word document with varying degrees of success (starting at not at all).
You shouldn't use Word for exchanging information anyway: attaching Word files to messages can actually be harmful to the sender; with Word, YGMTYS (You Get More Than You See). (Jonathan de Boyne Pollard's Frequently Given Answer on sending Word documents can tell you more about the disadvantages of Microsoft's proprietary file format.)
If plain text cannot convey your message, PDF is a reasonable format, since your correspondents likely already have a PDF reader, and if not they should be able to get one from Adobe.
Even how you package the words you write can be something to consider. If you gussy them up with fancy fonts and links to web pages, at least pity the poor folk who want or need just the words themselves in plain unadorned text. Messages without a text/plain version are extremely annoying to visually impaired people: feeding bloated, program-generated HTML to a text-to-voice system just does not work.
For sending to me, please read my preferences.
Specify appropriate attachment types. The content type of an attachment should describe it correctly and precisely, so that the recipient's e-mail program will know how to deal with it. Thus a PDF document should be labeled application/pdf rather than application/octet-stream. The latter is truthful (since it applies to any file), but about as useful as saying that New York City is located in the Milky Way.
Fortunately, most mail programs are pretty good at setting the content type to something reasonable; although lately I've been seeing more poor choices, some a little strange (e.g., video/x-flv instead of application/pdf for a PDF file).
Do not make your message look like spam. With so many people filtering out spam it may get lost.
For example, junk mail is often sent with the header field Content-Type: text/html, so don't do that. (I have observed that 99.44% of all messages with this content type in the message header (rather than just in an attachment header for an alternative version of the message) are spam, so I filter them out.)
How to get past my spam filter. If, despite what I say above, you really want to send me a message that looks like spam, or you think that your mail is not getting through for whatever reason, you can bypass the spam filter by using PGP to sign the message (with your private key) or to encrypt it (with one of my public keys), or by putting the phrase "[for JWW]", including the brackets, in the Subject line.
A reply to a message from me also bypasses the spam filter. (This works when you use your e-mail program's Reply function, so that the message header In-Reply-To or References line shows the Message-ID of my message. If you simply compose a new message, it will get no special treatment.)