Try sending an email with only addresses in the BCC field (ie none in the To or CC fields) and when it is delivered each address will appear in the To field, but only the recipient's will be displayed.
Bcc means blind carbon copy. To use it enter the correct email address for the blind carbon copy recipient of your message. To send an email to multiple recipients using Bcc, enter their email addresses, separate the email addresses with commas. Eg: firstname.lastname@example.org, email@example.com, firstname.lastname@example.org. The use of any other punctuation mark to separate multiple email addresses will result in an error.
Blind carbon copies are usually sent to recipients who may need to read what is being written without the other recipients knowing that they are receiving the email. Thus "blind" means that the identity of these recipients is hidden from all other recipients of the email. Only you the sender and each "Bcc" recipient will know that he/she has received a copy.