I suggest you look up Blind Carbon Copy (BCC) to understand how you get a delivery. It really has the same meaning it had when a typist placed it on a triplicate copy to the board or the legal team, except email does not make it clear it is a BCC. This page offers a fairly succinct discussion BCC https://www.technology.pitt.edu/help-desk/how-to-documents/using-blind-carbon-copy-bcc-feature-protect-privacy-email-addresses But beyond it's stated purpose it is becoming increasingly used by spammers to disguise the fact the mail has tens of thousands of recipients as the BCC list is not disclosed to the receiving mail server, unlike the to and CC lists where all recipients are disclosed. Only the fact that this mail account has a BCC mail to be delivered is disclosed when BCC is used.