In an email, what is the purpose of using the 'Bcc' field?

The 'Bcc' field in an email serves the specific purpose of sending a copy of the email to recipients without disclosing their addresses to one another. This is particularly useful when you want to maintain the privacy of each recipient or when sending messages to a large number of people where you may not want them to see who else is included in the email. By using the Bcc field, recipients are unable to view each other's email addresses, which helps reduce the risk of spam and protects their privacy.

In contrast, the other provided options do not accurately reflect the role of the Bcc field. For instance, allowing all recipients to see each other’s addresses pertains to the 'Cc' (carbon copy) field, not Bcc. This field is not related to the size of emails or the speed at which they are delivered. Those functionalities are influenced by factors such as email content or server efficiency rather than how recipients are included in the message.