It may seem very out dated, but how you respond & send emails says a lot. When responding to emails from a prospective job it is best to remember that the email is their first impression.
Make sure to check spelling, grammar and punctuation; you will be a face of their company that the public sees. You want them to see you as an asset and not a liability.
I know when I am driving to work & see a company's vehicle I judge the company by how the person drives; proper turn signals, road courtesy, cell phone usage (is the person on their phone), things that usually I don't expect of other drivers; if it is a vehicle with a company's name on it, I notice.