One of the greatest skills any person can have, whether they are a writer or not, is the ability to read, understand and follow directions. Agents, publishers, editors and blogs — you’ll find instructions for submissions pretty much everywhere you turn.
I run two promotional blogs and out of hundreds of submissions I still get the occasional email from a person who can’t be bothered to read and follow the simple instructions I have listed. It drives me up a wall. Now imagine the editor you just submitted to, the agent you just submitted to, the publisher you just submitted to having my same reaction. The difference between their reactions and mine is that I would email for a correction. The agent/editor/publisher will just send along a rejection letter and move on to the next person who CAN read and follow instructions.
Every agent/editor/publisher has a different set of submissions procedures. You can’t assume because you’ve sent in a few that they will all want the same thing. Some want a query letter. Some want a query with a synopsis. Some want the query, synopsis and sample chapters. And some don’t want anything but the full manuscript.
Everybody is busy and trying to cram as much work into a day as possible so they can get it all finished. Agents/editors/publishers use that first contact submissions email as a way to weed out people they don’t want to deal with. If a person can’t be bothered to follow simple instructions from a website, then that same person might turn out to be a pain to work with. Word one of your submission wasn’t read because you got eliminated on a technicality.
Read, reread and double check.