Mac OS X's Mail program has a very handy feature called 'Previous Recipients' that does a very nice thing: It saves a list of every person and email address you've ever sent an email to. Then, it automatically fills in that person's email address when you type it or the person's name in the 'To' field in a new message. This is usually a good thing, because it saves you time (you don't have to look up the address again!).
However, there are times when you want to send an email to a specific email address for that person, and the email address that Mail automatically inserts is—gasp!—the wrong address. For example, I want to send an email to my friend John, so I type in "John" in the To field. Mail fills in the address I usually send emails to: [email protected]. But I want to send the mail to John's alternate address, [email protected]... and I want to start sending emails to that address rather than to his first email address all the time. There are two easy solutions to this problem: