Email, Messaging, & Video Calls Email How to Use To, Cc, and Bcc With the Thunderbird Email App Thunderbird's Cc, Bcc, and to fields are how you send email messages By Heinz Tschabitscher Writer A former freelance contributor who has reviewed hundreds of email programs and services since 1997. our editorial process Heinz Tschabitscher Updated October 21, 2019 Nipitphon Na Chiangmai / EyeEm / Getty Images Email Yahoo! Mail Gmail Tweet Share Email Regular messages are sent using the To box in Mozilla Thunderbird, but you can also utilize the Cc and Bcc fields to send carbon copies and blind carbon copies. You can use any three to send emails to multiple addresses at once. Use Cc to send a copy to the recipient, but it will not be the "primary" recipient, meaning that any other group recipients will not reply to that Cc address if they reply normally (they'd have to choose Reply All). You can use Bcc to hide other Bcc recipients from each other, which is a good idea when protecting the privacy of lots of recipients, like if you're sending an email to a huge list of people. Email a Few Recipients You can add Bcc, Cc, or regular To recipients in two different ways, and the one you choose should depend on how many addresses you're emailing. To email just one or a few recipients using the Cc, Bcc, or To field is easy. In the message window, you should see To: off to the left side under the "From:" section with your email address. Input an email address into that box to send a regular message with the To option. To add Cc email addresses, just click the box that says "To:" on the left, and then choose Cc: from the list.The same concept applies to using Bcc in Thunderbird; just click the To: or Cc: box to change it to Bcc. If you enter multiple addresses separated by a comma, Thunderbird will automatically split them into their own "To," "Cc," or "Bcc" sections in their own boxes below each other. Email Lots of Recipients To email several email addresses at once can be done through the Address Book in Thunderbird. Open your list of contacts from the Address Book button at the top of the Thunderbird program window. Highlight all of the contacts that you want to email. You can choose multiples by holding down the Ctrl button as you select them. Or, hold down Shift after you choose one contact, and then click again further down the list to automatically select all the recipients in between. Once the desired recipients have been highlighted, click the Write button at the top of the Address Book window. You can also right-click the contacts to choose Write, use the Ctrl+M keyboard shortcut, or navigate to the File > New > Message menu item. Thunderbird will automatically insert each address into their own "To:" line. At this point, you can click the word To: off to the left of each recipient to choose whether to change the send type to Cc or Bcc.