Acknowledge E-Mails - Avoid Confusion, Misunderstanding

There are many times that I am not in a position to respond immediately to an E-Mail that I have received. In such a situation, I make sure that I send a short message acknowledging receipt of the E-Mail and inform the sender that I will respond soon. This way, the sender does not have to wonder whether their E-Mail has reached me in the first place or wonder as to why I have not responded to their E-Mail.