Configuring Sendmail on Solaris – Step-by-Step Guide

 

In many enterprise environments, servers should not send emails using their local hostnames. Instead, outgoing emails must appear as if they are sent from a centralized corporate mail server or domain. This blog walks through configuring Sendmail on Solaris using SMF (Service Management Facility), along with validation and testing steps.

This guide is especially useful for Oracle E-Business Suite/application servers running on Solaris that rely on Sendmail for outbound notifications.

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Prerequisites

• Solaris OS with Sendmail installed

• Root or equivalent privileges

• Access to corporate mail relay/server

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Step 1: Stop the Sendmail Service

Before making any configuration changes, stop the Sendmail service to avoid conflicts.

svcadm disable -t network/smtp:sendmail

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Step 2: Verify Sendmail Service Status

Confirm that the service is stopped.

svcs -a network/smtp:sendmail

The status should indicate disabled or maintenance.

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Step 3: Backup Existing Configuration Files

Always take a backup before modifying Sendmail configuration files.

Navigate to the Sendmail configuration directory:

cd /etc/mail/cf/cf

Create a copy of the existing sendmail.mc file using the hostname:

cp sendmail.mc `uname -n`.mc

This ensures you can easily identify the configuration per host.

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Step 4: Edit the New Configuration File

Edit the newly created .mc file:

vi `uname -n`.mc

Add the following line to configure masquerading:

define(`SMARTHOST', `mail.server-mycompany.co.in')dnl

Note: Replace mail.server-mycompany.co.in with your actual corporate mail server or domain name.

This setting ensures that outgoing emails appear to originate from the specified mail domain instead of the local server hostname.

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Step 5: Build the Sendmail Configuration File

Use m4 to generate the .cf file from the .mc file:

make `uname -n`.cf

This command converts the macro configuration into a Sendmail-readable format.

Add the mail server name in the configuration file

vi `uname -n`.cf

# "Smart" relay host (may be null)

DSmail.server-mycompany.co.in

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Step 6: Install the New Configuration File

First, back up the existing production configuration:

cp /etc/mail/sendmail.cf /etc/mail/sendmail.cf.`date +%d-%b-%Y-%H-%M`

Now, replace it with the newly generated configuration:

cp `uname -n`.cf /etc/mail/sendmail.cf

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Step 7: Restart the Sendmail Service

Enable and start the Sendmail service:

svcadm enable network/smtp:sendmail

Verify the service status again if needed:

svcs network/smtp:sendmail

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Step 8: Send a Test Email

Use mailx to send a basic test email:

mailx -s "Test Mail" -v jxxx@yyyy.zzz < /dev/null

Confirm that the recipient receives the email and that the From address shows the masqueraded domain.

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Step 9: Test Mail Server Connectivity

Validate SMTP connectivity to the mail server:

telnet mailserver.com 25

A successful connection indicates that the server can reach the mail relay on port 25.

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Conclusion

By configuring Sendmail , you ensure consistent and compliant outbound email delivery from Solaris servers. This setup is critical in enterprise environments where mail policies require all applications and servers to send emails through an approved mail domain.

Following these steps also minimizes downtime and allows safe testing before applying changes to production.

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