Nowadays, immediacy is the norm. Mobile phones offer the possibility of constant contact, and app and media stores offer instant downloads of purchases. When we're required to wait for something, such as a reply to an email, we often feel slighted as if a lack of immediate response means we're not important. Sometimes it doesn't, and here's why.
This quote from author William S. Burroughs sums up why you shouldn't necessarily be offended if a reply takes some time:
When my correspondents reproach me for tardiness, I can only say that I give as much attention to a letter as I do to anything I write, and I work at least six and sometimes sixteen hours a day.
Not only are we busier than ever, but writing a thoughtful reply to an email — regardless of how long that email turns out — requires effort. While most of us reply to the messages we find most import within 11 hours, we have a tendency to define "important" as "urgent" and urgent isn't necessarily a good thing. If it takes someone a while to reply to your email, it's worth considering that this extra time may be a good thing because it allows for a better and more thoughtful response. Or, at least, it's a relevant excuse next time someone reproaches you for your tardiness.