The trick is to use BLIND CARBON COPY or BCC.
Step 1:
At the top of your message type your own email address, so it says
To: yourusername@yourprovider.com
Step 2:
On the next line. use the pull down in the address section and select bcc:
Type in all the email addresses you wish to receive your message, using a comma to separate them.
BCC: frienda@herprovider.com, friendb@hisprovider.com.au.....
Step 3:
Send the email confident that only you will know who you sent it to.
Your recipients will only see that you sent them a message and you sent it to yourself. Their privacy is thus assured because of your courtesy in using Blind Carbon Copy.