Joshua Palmatier

I suppose the decision to omit the honorific would depend upon the querier's sense of written etiquette. While it is no doubt perfectly proper to address a letter to "Dear John Smith," I believe many would prefer to start the missive with "Dear Mr. Smith." I certainly would not use the first name only in an initial query, nor would I fall into that agent hating trap of "Dear Agent," or "Sir" or "Madam."
Dave