Answer: bccs

AnswerCrossword Clue
BCCSIncludes in an email unbeknownst to other recipients
BCCSSecretly keeps in the email loop, briefly
BCCSE-mail options
BCCSIncludes in an e-mail without other recipients knowing
BCCSSecretly adds to emails
BCCSHidden copies of an e-mail
BCCSSecretly includes on an email
BCCSIncludes surreptitiously
BCCSCovertly drops a line to
BCCSEmails discreetly