Cover letters to recruiters are different than letters to employers and should have:

• An address to a specific recruiter (whenever possible).
• The Job Title and # if it is in response to a posted advertisement.
• Three to six titles of positions for which you are qualified and interested.
• Enough skills and achievements to entice the recruiter to want to read your resume (your résumé should entice the recruiter to want to speak with you and / or meet with you.)
• Your geographic preference (cities, states, regions, countries) and willingness to travel.  "I am open to relocation anywhere in the United States and willing to travel extensively for the right position."
• Your salary requirement.  "My salary requirement is in the range of $80K to $90K, however I am open to negotiation based on the responsibilities of the position and the total compensation offered."

Most recruiters prefer to receive cover letters and resumes electronically via e-mail as attachments in MS Word format, ASCII files in the body of e-mails or website, or PDF files.  I recommend calling to find out the preferred version or sending all 3 versions.  If possible, follow up with a hard copy by snail mailed.  So few people do this that recruiters often will read them.

One recruiter told me that she receives so many resumes by e-mail on Mondays that she automatically deletes all of them.  If you e-mail cover letters and resumes, avoid Mondays and send hard copies as a back up.

You may want to follow up with a phone call to make sure your e-mailed or snail mailed file was received and to make contact with the recruiter.