When you send an email to many people and put their addressses in the Carbon Copy (CC) field, they will be able to see each other’s addresses. Some recipients may not appreciate this. Instead, place them in the Blind Carbon Copy (BCC) field.

For more on BCC, please visit whybcc.com because I couldn’t have said it better.

For more email ettiquette tips, I recommend 101 Email Etiquette Tips. Please pay special attention to #42 & 58.