What is the “To” field?

The To field is the human facing label for the recipient. Actual delivery still happens through the invisible RCPT TO commands during SMTP.

When all recipients are placed in BCC some mail clients write Undisclosed Recipients in the To header. That line is only there so the message does not look empty. It is cosmetic.

It is the addressee on the letterhead. People read it. Servers do not rely on it.

Was this answer helpful?

Thanks for your feedback!