Recipients can be added in three ways:
addTo(): Adds a recipient to the mail with a "To" headeraddCc(): Adds a recipient to the mail with a "Cc" headeraddBcc(): Adds a recipient to the mail not visible in the header
getRecipients() serves list of the recipients.
clearRecipients() clears the list.
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.
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.