Integrating Sendmail with Email Delivery

Configure Sendmail to Send Email Through Email Delivery

Sendmail is a general purpose internetwork email routing facility that supports many kinds of mail-transfer and delivery methods, including the Simple Mail Transfer Protocol used for email transport over the Internet. You can use Sendmail to send emails through Email Delivery. Before you use Sendmail you must configure Oracle Cloud Infrastructure Email Delivery in your Sendmail application.

To enable Sendmail to integrate with Email Delivery:

1. Make sure Email Delivery is configured to send email. See Getting Started.

   Note
   
   

   SMTP credentials are required to configure Sendmail to use Email Delivery. Be sure to note the user name and password when you generate the SMTP credentials.

2. Run the following update and install commands:

   sudo yum update
   sudo yum install sendmail sendmail-cf m4 cyrus-sasl-plain

3. Update /etc/mail/authinfo. Run the following command:

   sudo vi /etc/mail/authinfo

   Note
   
   

   If /etc/mail/authinfo doesn't exist, you can create it by running the command sudo vi /etc/mail/authinfo.

   Add the following line:

   AuthInfo:<SMTP connection endpoint> "U:root" "I:<username from smtp credentials>" "P:<password from smtp credentials>" "M:PLAIN"

4. Generate the /etc/mail/authinfo.db file.

   Run the following command:

   sudo sh -c 'makemap hash /etc/mail/authinfo.db < /etc/mail/authinfo'

5. Add support for relaying to the Oracle Cloud Infrastructure Email Delivery SMTP endpoint.

   Run the following command:

   sudo sh -c 'echo "Connect:<SMTP connection endpoint> RELAY" >> /etc/mail/access'

6. Regenerate /etc/mail/access.db.

   Run the following command:

   sudo sh -c 'makemap hash /etc/mail/access.db < /etc/mail/access'

7. Create a backup of the sendmail.cf and sendmail.mc files.

   Run the following command:

   sudo sh -c 'cp /etc/mail/sendmail.cf /etc/mail/sendmail_cf.backup && cp /etc/mail/sendmail.mc /etc/mail/sendmail_mc.backup'

8. Update the /etc/mail/sendmail.mc file.

   Run the following command:

   sudo vi /etc/mail/sendmail.mc

   Find the MAILER() definitions.

   Type /MAILER and press ENTER.

   In Insert mode, add the following settings before any MAILER() definitions:

   define(`SMART_HOST', `<SMTP connection endpoint>')dnl
   define(`RELAY_MAILER_ARGS', `TCP $h 587')dnl
   define(`confAUTH_MECHANISMS', `LOGIN PLAIN')dnl
   FEATURE(`authinfo', `hash -o /etc/mail/authinfo.db')dnl
   MASQUERADE_AS(`<sending_domain>')dnl
   FEATURE(masquerade_envelope)dnl
   FEATURE(masquerade_entire_domain)dnl

   Disable Insert mode.

9. Make Sendmail writeable.

   Run the following command:

   sudo chmod 666 /etc/mail/sendmail.cf

10. Regenerate sendmail.cf.

    Run the following command:

    sudo sh -c 'm4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf'

    Note
    
    

    If you receive an error, such as "Command not found" or "No such file or directory," confirm that the m4 and sendmail packages are installed on your system.

11. Reset permissions for sendmail.cf to read only.

    Run the following command:

    sudo chmod 644 /etc/mail/sendmail.cf

12. Restart Sendmail.

    Run the following command:

    sudo /etc/init.d/service sendmail restart

13. Test the configuration by sending a test email.

    Run the following command:

    /usr/sbin/sendmail -vf <from_email_address> <recipient_email_address>

    Enter the details of the email. After each line press Enter.

    For example:

    From: <from_email_address>
    To: <recipient_email_address>
    Subject: OCI Email Delivery test email
    This is a test message sent from OCI Email Delivery using Sendmail.

    Press Ctrl + D to send the email.

14. Verify receipt of the test email.

    Note
    
    

    You can troubleshoot an issue by reviewing the Sendmail log on your mail server, located at /var/log/mail.log.