sendmail is MTA (Mail Transfer Agent)

mailx is MUA (Mail User Agent)

Usage

mail -s "Subject" devin.chen@gmail.com
/bin/mail -s "Subject" devin.chen@gmail.com
mailx -s "Subject" devin.chen@gmail.com
/usr/bin/mailx -s "Subject" devin.chen@gmail.com

input

Ctrl+D to finish

发送邮件

echo -e "Email content" | mailx -v -s "Email subject" -S smtp-auth=login -S smtp=smtp://mail.bar.com:25 -S from="foo@bar.com(Notify)" -S smtp-auth-user=chenyangf@bar.com -S smtp-auth-password=123456 foo@gmail.com

FAQ

send-mail: fatal: parameter inet_interfaces: no local interface found for ::1

https://www.centos.org/forums/viewtopic.php?t=42362

/etc/postfix/main.cf

inet_interfaces = 192.168.0.78

/etc/init.d/postfix restart

References