You need to create a distribution list, aka "Group", within Address Book first of the users you want to send an e-mail to. How?
1.) Highlight all 50 messages in your Inbox and hit the "Add Address" button (you may need to add this to your Mail toolbar if not present)
2.) Open up Address Book
3.) You should now see all 50 e-mail addresses of the unique users from your Inbox you just added
4.) Now, hit the "+" button to add a new "Group" within Address Book. Give this new group a name.
5.) Now, within Mail, compose a new message and in the "To" field, type the name of the newly created group you just made within Address Book.
6.) Press send.
7.) Come back here and thank rickey939.
