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.
Remember, you're hoping the person who receives your letter has no memory of your closing at all. The last thing you want is a hiring manager going into an HR meeting with your cover letter in hand, asking the team if they want to meet with "Mr. Kindest Personal Regards."