For sure! To send your message to more than one person, add the additional email addresses in the "To:," "Cc:," or "Bcc:" fields. If you have more than one address in a field, separate them with commas. For example:
To: johndoe@yahoo.com, janedoe@yahoo.com, jimdoe@yahoo.com, etc.
If you don't enter valid email addresses, or if you don't use commas to separate your recipients' addresses, your message won't be sent. Instead, you'll see the message, "Unfortunately, there was a problem: There is a syntax error in your To, Cc or Bcc field..."
Note: Sending junk mail or "spam" is a violation of the Yahoo! Mail Terms of Service and will not be tolerated.