"mailx" and "dead.letter" and "centos"

C++
set smtp=smtps://smtp.gmail.com:465
set smtp-auth=login
set [email protected]
set smtp-auth-password=YOURPASSWORD
set ssl-verify=ignore
set nss-config-dir=/etc/pki/nssdb/
vi /etc/mail.rc
Source

Also in C++: