This doesn’t have much to do with being a writer or author but it does have something to do with the business side of this literary field, check and respond to emails promptly. If you are serious about your literary career, check your emails often and respond. No business person like to do with delays emails. It is today’s way of communication so answer and respond as if you were answering the phone when you hear it ring.
Be professional in all aspects of your literary career!