How can I send email to many people but the recipient only sees himself as the recipient?

I have build a category and consist of thousand of names. I want to shoot out a single email without the recipient sees other email address

How can I send email to many people but the recipient only sees himself as the recipient?
Put all the email address into the BC (blind copy) adress line that way they will only see their name.
Reply:Use the BCC option in express (blind carbon copy)