our domain Is abc.com and our COO's email address is firstname.lastname@example.org ( his full name is john smith ) . our internal users are getting lot of mails email@example.com , firstname.lastname@example.org as fake emails . we undershoot that type of can reach our internal mail users .
but yesterday we got a mail email@example.com and display name as COO . so any one can send email using our email domain name ?
one of my friend told me that some internet sites facilities that type of email address . My question is without any user name in our AD/exchange possible to send the emails using our domain name abc.com ?
if yes how we know the genuine email address .