Slyly include in an email, for short

• Include in an email secretively
• Secretly loop in
• Private email attachment, briefly
• Privately include in an email: Abbr
• Include in an e-mail without other recipients knowing
• Emailing option
• Email option, briefly
• Include discreetly in an email, for short
• Covert communication

Wiktionary Word definitions in Wiktionary
init. 1 body-centered cubic 2 blind carbon copy vb. to send something by blind carbon copy