How to Send Mail via External SMTP server using mailx command in Linux?

By default, the mail command in Linux will make use of the local SMTP server running on port 25 for sending mails. But if you want to send mails using external SMTP server such as smtp.gmail.com or  SMTP server of your organization, then you can use mailx command. Using mailx command is quite easy, all you need to do is install mailx package and pass few SMTP related arguments to the command

Install mailx on RHEL/CentOS:

# yum install mailx

Install mailx on Debian/Ubuntu:

# apt-get install mailutils

Send mails with External SMTP server using mailx command:

# echo "The actual message goes here" | mailx -v -r "user@domain.com" -s "The actual subject line goes here" -S smtp="smtp.domain.com:587" -S smtp-use-starttls -S smtp-auth=login -S smtp-auth-user="user@domain.com" -S smtp-auth-password="password123" -S ssl-verify=ignore the_recipient_email@domain.com

Note: Make necessary changes in the above command – such as smtp server address, port, connection type, smtp username and password.