The story ends with a guy having a "stumpy, sulfur trussed antelope" in front of him, while a "stomped 'sylph' addressed cantaloupe" is on his desk when he is supposed to have received a "stamped self addressed envelope".
This is Author, Author by Tim Colley, published in Isaac Asimov's Science Fiction Magazine, v. 5, no. 1, published 1981.
Grabbing the lens, the Editor could just make out a tiny label with these words almost hidden by dribbled juice: Send to Sylph. "So what?” "I would deduce our friend here has been eavesdropping. Perhaps sound in his universe is less distinct than here, or his hearing may just be poor. Perhaps he’s heard you laying down the law to some aspiring author: certainly he knew that any unsolicited manuscript had to be accompanied by a stomped, Sylph-addressed canteloupe.” "How laborious.” The Editor groaned and turned the ice-pack to high. "But when you rejected his first submission, he must have thought he mis-heard you. So here he is again . . .” "With a stumpy, sulphur-tressed antelope,” completed the Kindly Editor, pounding softly on his desk.
You can find the full text at the Internet Archive
I think it is in Asimov Laughs Again, right by "Death of a Foy." I have a copy, let me check. update still looking for my copy, it seems to be misplaced. Update 2: I did find my copy of Asimov Laughs Again; sadly that particular story isn't in it as far as I can tell.