Outlook 2010 calls it “Delayed Delivery.” Delayed Delivery allows you to specify a date and time when you want your email delivered.

Write your email, filling in your To and Subject lines.
Instead of “Send,” go to “File” and “Save” – it will be filed in your “Drafts” folder.

Go to your Drafts folder and open (double click) the email you just typed.
Click on the “Options” menu at the top.
Look for the option called “Delay Delivery” and set your delivery options.

Image: Timed Email