For those who are looking to the solution to adding cc and bcc in PEAR php mail. Here is the simple solution and the abbreviated explanation why.
ANSWER: Everyone who want to receive the mail must be added to the $recipients
field. If they are not in this field, they will not get the mail. Everything you want to be visible, add to the header. Therefore, since bcc is BLIND carbon copy, do NOT add it to the header.
WHY?: The recipient field dictates where the mail goes, the headers dictate what is displayed. If you do not add cc to the header, then you can make them blind too. Whichever tickles your fancy. Any questions, check the link ripa added above! Great explanation!