However, when you send an email message to almost any other group, privacy may be a concern. The recipients of your message may not appreciate having their email addresses revealed to people they may not even know. The courteous thing to do is to use the BCC (blind carbon copy) option to send your message. When the BCC option is enabled, it shows up as an additional field where you can enter recipients’ email addresses. Unlike the similar CC (Carbon Copy) field, email addresses entered into the BCC field remain hidden from other recipients of the same email.
Hidden Danger of the BCC
BCC seems like a good way to send emails to a group of people without letting everyone know who is on the list, but this can backfire when a person who received a BCC email chooses to Reply to All. When this occurs, all email recipients on the To list and CC list receive the new reply, inadvertently letting others know that there must have been a BCC list as well as the public list of recipients. Aside from the person on the BCC list who chose the Reply to All option, no other member of the BCC list is exposed. The point being, the BCC is an easy way to hide a recipient list, but like most easy ways of doing things, it has the potential to be easily undone.
How to Enable the BCC Option in Mail
The process of enabling the BCC field varies slightly, depending on the version of macOS or OS X you’re using.
Turn the BCC Option On or Off in macOS Catalina through OS X Yosemite
The BCC address field isn’t usually enabled by default in Mail. To enable it:
Turn the BCC Option On in OS X Mavericks and Earlier
The process for enabling and using the BCC field in earlier versions of OS X is nearly identical to the current method. The only difference is where the visible headers field icon is located. In older versions of Mail, the icon is located to the left of the From field in the new message window. To turn off the BCC address field, go back to the drop-down menu and click BCC Address Field again. This removes the check mark next to the menu item and turns off the BCC field.
Turn the BCC Option Off in OS X Mavericks and Earlier
To turn off the BCC address field, click the pop-up menu to the left of the From field and select BCC Address Field again to remove the check mark next to the menu item. When you enable the BCC field, it appears on all future email messages in all your Mail accounts (if you have multiple accounts).