Email Confidentiality Clause How To I Send My Friends Email As "an Undisclosed Recipient"?

How to I send my friends email as "an undisclosed recipient"? - email confidentiality clause

I do not want, so that everyone knows that I can send emails, or what would prevent my friends is.To email address confidentiality.I opinion of many people who protect them, but I do not know how done. help S 'please!