If you use Chronicle to send email outside of your organization and you want the person you're sending the message to see who else you are including from inside your organisation, change your default communication settings to "Internet Email" for yourself and any other employee who should be visible to outside recipients. This treats all messages like any other email program, and anyone on the outside of your organization can see the other internal recipients on an email. When set to "Chronicle Messaging" (which is the default), only people inside your organization can see internal recipients; anyone outside will only see the sender and no other internal recipients.
You can quickly change this preference by going to the people tab and selecting all active employees. For any employee who needs this changed, open up their file and on the General tab you'll see the setting for the default way to communicate (see screen shot below).