postfix で gmail経由でメールを送る
% sudo yum install postfix cyrus-sasl
% sudo chkconfig -add postfix
% sudo chkconfig postfix on
relayhost = [smtp.gmail.com]:587
#sasl setting
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options = noanonymous
smtp_sasl_tls_security_options = noanonymous
smtp_sasl_mechanism_filter = plain
#tls setting
smtp_use_tls = yes