A "cold call" is an initial communication with someone who doesn't know you. I've gotten a lot of email cold calls over the years that have left me scratching my head wondering how to respond. This has prompted me to compile a few hints on how to compose a cold-call email. By following a few simple rules you can make it a lot easier for the person you are contacting to respond effectively.
These rules really boil down to one of the cardinal rules of communication: know your audience. This rule runs both ways, and is particularly problematic for cold calls because almost by definition you don't know your audience, and your audience certainly doesn't know you, which makes it that much harder for them to frame an appropriate response. So the object of the game is, first, to learn as much as you can about the person you are contacting *before* you contact them, and then give them as much information about yourself and what you want as you can without getting long-winded.
0. Know your audience. Find out as much as you can about the person you are contacting before you contact them. You don't have to become their biographer, but you should at a minimum do a quick web search. If the person has a home page, read it.
1. Introduce yourself. A sentence or two is all it takes. If you can't come up with anything better, start with "My name is..." If you are writing in connection to your work, give your title and company. If you are a student, give your status (grade level, undergraduate year, or graduate level) and the school you attend. In short, say something about yourself to help your contact anchor their first impression of you and tailor their reply appropriately.
1a. If you are not fluent in your audience's native language, give some kind of a hint what your native langauge is. If you are writing from an institution located in a country where your native language is spoken that's good enough. But if you are, say, a native Farsi speaker who is living in Canada then you should say something like, "I am a visiting scholar from Iran currently at the University of Toronto." Knowning where you are from will help your audience filter out any language stumbles. It will also give them the opportunity to respond to you in your native language if they happen to know it. You never can tell.
2. Say a few words about what you are doing that motivated you to contact this person. Were you referred by someone? If so, who? Did you find some information on the web? If so, what was it?
3. If you want the person to do something for you that you expect will take more than just a few minutes, don't ask directly. Instead, ask if the person can spare some time and give a general idea of the magnitude and character of the task. For example, "Could you spare fifteen minutes to answer some questions about Australian Aboriginees?" is much better than, "Please answer the following fifty questions ..."
4. If you are asking for information, say what efforts you have already made to get it. Where did you look, and what did you find? As a bare minimum you should do a quick Web search before asking anyone for anything nowadays. If the person you are contacting has a home page, read it.
5. Make it easy for your contact to reach you and learn more about you. Put your email address at the bottom of your message. If you have a home page, put the URL there too. Some mail systems munge return addresses so that replies don't work, and this may be the only way your contact has of reaching you.
One last minor point: if you aren't sure about how to address someone, just open with "Hello."
(NOTE: This was originally written a long, long time ago. I recently (May 2010) replished it as a blog post if you want to comment on it.)