to  (String)  specifies the email address(es) of recipient(s), each using standard unadorned email address format. (e.g. tom@microsabio.com). If you are specifying multiple addresses, separate them with chr(13) characters. (Up to 100 addresses allowed.)

Note that if you plan to use the CC: or BCC: header items to send copies of the message to other people, those people must be listed here in the to parameter. (This parameter is strictly used by the SMTP server for routing and does not (usually) show in the recipient’s message header.)