If you have a BCC function available, just insert the e-mail addresses as such:
Code:
person1@domain.com, person2@domain.com, person3@domain.com
Notice the comma and the space between each address.
If you don't have a BCC function, in the CC box, enter the email addresses as such:
Code:
(person1@domain.com, person2@domain.com, person3@domain.com)
Notice the parentheses: If you use parentheses in the CC box, it should send the mail to those recipients as a BCC.