You may chose to block form submitting or disable notification(s) / mails when user's enter match your blacklist / white list / email list mapping.
Contact Form 7 have two default mails to sent out. You may choose to skip the main mail or additional mail together.
Decided by the mail logic of Contact Form 7 you if you choose to skip the main mail then additional mail / Mail (2) will also be skipped. It means you may just skip additional mail / Mail ( 2 ).Purchase Contact Form 7 Blacklist