About a week ago, I posted an open question
about if I should politely (and nicely) respond when I get a "nice no" on a submission, ie a "no" with a few feedback comments from the editor.
The general trend of responses was to *not* respond, as inbox management is a constant concern for all editors.
However, if the feedback was very very extensive then a "wow, thank you" email would be very appropriate.
Also, if the feedback led to a critical insight about the story that helped with a revision and an eventual sale, that would be a good occasion for a thank you note.
Finally, one might put a short "thanks for the good feedback on my previous submission" mention in the cover letter for the next submission.
My experience up to now has been that the only times I got detailed feedback they were part of a revision request associated with a sale. These recent cases, obviously, weren't quite like that. No dancing and cheering occurred. :-)
I didn't respond to everyone in the original LJ post, as it was a lot of posts, but thank you to everyone for their input! I greatly appreciate it.