There are some emails from prospective clients I do not feel obligated to answer. They are:
1. Are you accepting queries?
This falls into the category of TSTL.
2. Can I send you a query?
Not only TSTL, but incorrect use of can/may, thus improving your chance of a form rejection anyway
3. Do you consider children's/fantasy/zombie romance books?
Now, this might not be quite as obvious as 1 and 2, but here's the thing: just send the damn query. If I don't want to proceed, I'll reply.
If you send me an email about your work, assume it's a query. Compose accordingly.
For more genteel advice on the same subject, check out Jessica Faust's post.