Nopali includes a 'Mass Email' panel, allowing you to send an common email to a list of persons in bulk. The emails are sent individually, so the recipients will not see other recipients of the message.
To see the panel, select the 'Data>Show Mass-Emailing Panel' menu item:

You first formulate an email with a return address, subject and message in Step 1. You can also add attachments by pressing the 'Add Attachments' button.
Next, import email addresses. You can do this by dragging vCards into the table in Step 2. These vCards can be dragged from the Nopali Search Drawer or by dragging vCards from AddressBook. You can also drag tab-delimited text files into the table. If you prefer, you can select a number of patients in the Search Drawer and press on the 'Data>Send Selection To Mass-Emailing Panel...' menu item.
After reviewing the table, you can then press the 'Send To 'Mail'' button. Note that the Mass Mailer Panel uses the Apple 'Mail' application to send the messages, so a copy of the delivered message can be found in the 'Sent' box in 'Mail'. You should also leave the 'Mail' app open untill all of the messages are sent.