A Pen serves as a physical writing tool and a digital stylus which people use to create drawings and make digital inputs but it does not function as an essential technical element or standard feature or built-in protocol of the email system.
The term "Pen" describes a physical writing tool which does not function as an essential technical element or built-in protocol or standard feature of electronic mail (e-mail) systems.
Bcc: This stands for Blind Carbon Copy. It is a standard field used to send a copy of an email to recipients whose addresses remain hidden from other recipients.
The Pine (Program for Internet News and Email) application functioned as a terminal-based e-mail client which people used on Unix systems although it has become less popular in modern times.
The term Spam describes bulk unwanted email messages which businesses send to customers without their consent for advertising purposes or to spread harmful content.