For uploaded or mailed cover letters, you do not need to include as much information as you would in an email message, because the heading of your cover letter includes your contact information. For a paper cover letter, use a formal business_style letter format which includes a heading, salutation, the body of the letter, closing, and your signature. Review these guidelines for what to include in your letter.
Formal communication is on the wane in modern life, but there are still times when it's the only correct way to reinforce a connection or convey information. If you're applying for a job, looking for a recommendation, or expanding your network, err on the side of formality. Don't let the slightly archaic feel of a formal business letter tempt you into using flowery, outdated language.