Short and sweet today, but very important. This article on the Swivet gives some vital advice to anyone who is querying or who may be planning on sending out queries.
Nearly all agents have a "no attachments, please" policy. If you've ever queried before, you know this. Agents open hundred of emails a week and aren't going to risk their computer files (or waste their time) opening attachments from complete strangers. So the policy is: paste everything in the body of an email until I ask you specifically to send an attachment.
And if you don't? Nine out of ten, the agent will delete your query without giving it a second thought.
BUT apparently, so email clients and signatures could contain unsolicited attachments without you even knowing about it. Read the article and DOUBLE CHECK your email before querying!