I had written a manuscript and had got it verified by a Professor (as it was closely related to some of his work) who said it was correct. I later came to know that he is also an editor of a reputed journal. So I Wrote to him (the Editor of a journal (math)), asking to comment about suitability of the manuscript for that journal, even before submitting to the journal, is it ethical? and not something frowned upon?
PS : I have not submitted to that Journal.