Using Postfix:
service postfix status
Configure for a g-mail account
If postfix is not installed:
yum -y install postfix mailx cyrus-sasl-plain
edit /etc/postfix/sasl_passwd
smtp.gmail.com email@gmail.com:emailpassword
postmap hash:/etc/postfix/sasl_passwd
edit /etc/postfix/main.cf
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
samtp_sasl_security_options = noanonymous
# Secure channel TLS with exact nexthop name match.
smtp_tls_security_level = secure
smtp_tls_mandatory_protocols = TLSv1
smtp_tls_mandatory_ciphers = high
smtp_tls_secure_cert_match = nexthop
smtp_tls_Cafile = /etc/pki/tls/certs/ca-bundle.crt
relayhost = smtp.gmail.com:587
save file
service postfix restart
mail email@domain
rm /etc/postfix/sasl_passwd