If you are writing to a person whose name you know, always use Dear + their name. If you are writing to a company and you don't know who's going to read your e-mail, write Dear Sir or Madam. Be careful, though! it's always good to check the company's website and find out the right person to write to. Some companies tend not to read the e-mails/letters if the sender wasn't willing to find time to find the information.

First paragraph should always state why you're writing the e-mail. Make short introduction of a company and then write the reason for sending the e-mail. Don't forget to write the name of the company and the fact you're writing on behalf of them!

In the second paragraph you should briefly (!) introduce the company. It's a good idea to organize the information into bullet points. Try to choose information which is relevant for the potential partner's decision. If you refer to the company's website, put the link straight into the e-mail so that they can check it with one click.

If you have some references about the company, send them as the attachment of this e-mail. Don't promise to send them later as it could be too late for such an action.

In the last paragraph state what action you expect from the person you're writing to.

Don't forget about final statements and your name (plus status), which are obvious part of any formal e-mail.