A comma separated list of addresses for blind carbon copies (optional).
This property specifies a comma separated list of destinations for blind carbon copies of the mail message. A copy of the message is sent to each destination, but no BCc SMTP header is created containing the destination addresses, so individual recipients never see the list of the other recipients.
The component will return an error if the MailServer returns an error code about any email address specified in SendTo or Cc but it will only fire an Error event if the same happens with an email address specified in this property.
If the resulting header is longer than MaxHeaderLength, then it is folded according to RFC 822 specifications.
NOTE: You must clear the MessageRecipients collection before setting this property to remove previous recipients.