When addressing an email message, you can, of course, simply type email addresses into the provided address fields (To and Cc). However, you may wish to easily enter email addresses that you have not memorized and you may wish to display the hidden address fields, Bcc and Reply-To. In this section, I explain how to handle each of these addressing scenarios, and I discuss sending email to groups.
If you have multiple accounts (or email aliases), Mail’s New Message window displays a pop-up Account menu just above the message body. When you choose an email address from this list, Mail sets the From address accordingly, and sets the SMTP server to match the settings for that address.