This article is from the rec.arts.sf.composition FAQ, by Geoffrey Wiseman loki@mgl.ca with numerous contributions by others.
If an editor has a specific policy with respect to cover letters,
follow it. Otherwise, be brief. Most people with editing
experience will tell you that unprofessional cover letters are
a common mistake of amateurs.
Your cover letter should simply include any -relevant-
previous sales (no, not your article on hand-rolling cigarettes
for the school paper), and potentially that you've graduated
from Clarion, if you have. State that you're submitting a
story, attached, and end the cover letter there, while you're
still ahead.
 
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