Just to clarify: Through the first part of the year, I was getting about a 50% "Send me the manuscript" response, with the other 50% getting no response at all. I guess that's the new rule in email--no answer equals no.
However, since 50% did want to see the manuscript, I figure my query is okay.
But starting in late July and through August, I've sent out maybe 10 queries with only one request and nine no answers. Recently, two queries came back saying the recipient's mail box was full.
But I figure, what's the harm in re-sending queries to agents who didn't respond the first time? There's always a chance they didn't really read the query in the first place. Anyway, you can't do worse than get another no response from them.
In fact, though this is probably an example of shooting yourself in the foot, I've often thought of endlessly requerying some agents until they finally respond--just to show them that two can play at the rudeness game. Luckily, I haven't quite done that yet. Resending once has been my limit.
As far as snail mail, I think it's true that you get more responses. The one snail mail letter I sent out got a form rejection within a week, saying the agent was hardly taking on any new clients--which I guess I already knew.
But my email query has also been somewhat personally tailored to each agent. And whoever has read the full manuscript has always had some nice things to say, including "I'd love to see your next one."
Since I don't have a next one as yet--and there's no telling when (or if) I ever will have something this good again--I'm determined to push on with this one.