From Jordan Bass at McSweeney Books in response to a submission sent in April:
Hi W,R-thanks for sending in your manuscript, and sorry it’s taken us so long to respond. We rely on submissions like yours, since a good portion of what we publish comes to us unsolicited. Unfortunately, we won't be able to publish your book--we're a very small company, and can only put out a few each year. Thanks again for your efforts, though,
Form letter as email. Somehow the "Hi [first name]" and use of dash/hyphen, plus trailing off sytax, give this letter a cozy casual feel, but it's definitely a standardized rejection. They give good form, right?