I don’t want all email addresses showing when I send an email to lots of people at once. Do I combine all the addresses into one group?

Thanks!

I have a friend I need to email on his blackberry but I do not have his address with me and I cannot remember it. I know its his name and then something att blackberry and I am not able to call him right now to ask. Can anyone help me out?
I do not have any other email address for him. I thought I had his blackberry one saved in my outlook here at work but I do not.
majon.com

I want someone to quit emailing me and I can’t find on my yahoo mail to block someone.