Dear Wendy…

Indeed it is acceptable . . . under certain circumstances. The best scenario has the editor or agent giving specific revision suggestions along with an invite to resubmit should you revise along those lines. But even without an invitation, if you’ve revised the manuscript significantly (that word is important, because they didn’t say “no” due to surface problems—they’d probably work on those with you if that were the case), you can resubmit it with a note in your query letter saying, “I’ve changed the manuscript significantly since you last saw it and hope you’ll be open to taking another look.” If they’re not, they won’t. No skin off any noses.

Happy writing!

The Editor