Dear [first name],
Thank you so much for your submission, and for your interest in Lost Balloon. Unfortunately we feel this piece is not quite right for the magazine, so we will have to pass on it.
We did enjoy reading it, however, and hope that you will submit something else during our next open period.
We know that writing and submitting is hard, and we support your work. Best wishes in everything.
Sincerely, The Editors Lost Balloon