Be careful replying to all if you’re a “Bcc” recipient in Outlook
When you receive a message in which you are Bcc’d, other names in the To and Cc are not aware you were copied on an email. You will see other names that are in the To or Cc but names in the Bcc are not seen by others. If you “reply to all,” others may “discover” that you received a copy, which could cause embarrassment. So be careful before replying to all, and if your name is not listed in the To or Cc, you were Bcc’d in the message.
In addition, replying to all does not go to Bcc recipients. If you’re looking for the Bcc field, you have to click on the Options tab while in a message and click Bcc icon to add it. You will not see the Bcc field, however, if you are opening a message you received.