First, you write that it "insinuated" that your submission was fraudulent: defamation involves a statment by the other person that is objectively defamatory, not the alleged victim's personal or subjective belief that it is. Therefore, unless a statement would be seen by a reasonable 3rd party to be defamatory, it would not be.Second, defamatory statements must be "published" to 3rd parties, or spoken, shown, transmitted, etc. to 3rd parties. If the only person who saw this statement is you, that is *not* defamation. It may be insulting, but defamation involves showing or speaking the statement to 3rd parties, not only to the person the statement is about.Third, you can only sue for damages--that is, for the injuries you suffered. If this statement has not damaged you in your industry, has not cost you a job, has not harmed your professional reputation, etc., there are no damages for which you'd be compensated. The courts do not provide compensation for being upset or insulted or belittled unless there is some concrete harm that goes with it.From what you write, therefore, there may be several significant hurdles to having a valid claim.