There are many reasons you might want your email to arrive at a particular time, like wanting your mail at the top of someone’s inbox when they start work. You can do this in Outlook by scheduling your messages.
Before we go any further, we need to add a couple of caveats. First, sending an email at a particular time does not guarantee that it will arrive in your recipient’s inbox at that time. There are many steps between you sending an email and the email appearing in someone’s inbox. While you can generally assume that a message sent at 8:30 am will be in someone else’s inbox within a minute or two, don’t rely on it for critical delivery. The second caveat is that this only works for the desktop Outlook client, not the Outlook web app.