How do I use mailx with SSL?

To use mailx with SSL, you typically need to configure it to use an SMTP server that supports secure connections, as mailx itself does not handle SSL/TLS directly. Here’s a step-by-step guide on how to achieve this:

1. Identify an SMTP server with SSL/TLS support: You'll need access to an SMTP server that supports SSL or TLS. Commonly, services like Gmail, Microsoft 365, and many hosting providers offer such servers.

2. Configure `mailx` for SMTP with SSL: You will configure your mailx client through environmental variables or configuration file to communicate through SSL/TLS to a compatible mail server.

3. Set Up SMTP variables: This will be set in bash shell. Example values for Gmail will be used here, substitute them with your actual server and account values.

                             
export MAIL_SERVER=smtp.gmail.com
export MAIL_PORT=587
export MAIL_USER=your_email@gmail.com
export MAIL_PASSWORD=your_email_password
export MAIL_AUTH=login
                             
                         

Note: Instead of plain-text, use appropriate credential management technique on server level if possible.

4. Configure the `mailx` to utilize your environmental variables and SSL. You'll use `-S` flag and relevant options

Example mailx command to send email, given above variables:

                                
echo "Body of the email" | mailx -v -S smtp="$MAIL_SERVER:$MAIL_PORT" \
  -S smtp-auth=$MAIL_AUTH \
  -S smtp-auth-user="$MAIL_USER" \
  -S smtp-auth-password="$MAIL_PASSWORD" \
  -S ssl-verify=n \
  -S from="your_email@gmail.com" \
  -s "Your subject" recipient@example.com
                                
                            

5. Verify setup. Execute command. Check whether email was send successfully and check for error in logs, if any, such as problems with DNS resolution.

Key parameters:

- -S smtp=server:port: Specifies the SMTP server and port to use. Common port are 465 for implicit SSL and 587 for explicit TLS (STARTTLS).

- -S smtp-auth-user: Set the email address of your account

- -S smtp-auth-password: Password to login in specified email

- -S smtp-auth: Authentication method (login or similar) depending on the server's capabilities. In above scenario, use "login" mode for Gmail.

- -S ssl-verify=n: Can skip certificate checking, only in debug situation, or you are absolutely sure it is not going to cause any issues.

Note: The example command assumes your mailx version (typically "s-nail") includes the SSL connection features, verify its version.

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