Recipients can be added in three ways:
addTo(): Adds a recipient to the mail with a "To" header
addCc(): Adds a recipient to the mail with a "Cc" header
addBcc(): Adds a recipient to the mail not visible in the header
getRecipients() serves list of the recipients. clearRecipients() clears the list.
Note: Additional parameter
addTo() and addCc() accept a second optional parameter that is used as a human-readable name of the recipient for the header. Double quotation is changed to single quotation and angle brackets to square brackets in the parameter.
Note: Optional Usage
All three of these methods can also accept an array of email addresses to add instead of one at a time. In the case of addTo() and addCc(), they can be associative arrays where the key is the human readable name for the recipient.