Sendmail smart relay host ds

A blast from the past!

sendmail is a classic email transfer agent (MTA) that was widely used in the past, but has largely been replaced by more modern alternatives like Postfix, Exim, and OpenSMTPD.

That being said, I'll do my best to help you with your question.

smart relay host is a feature in sendmail that allows you to specify a relay host that can handle email delivery for your domain. This is useful when you don't have a direct connection to the destination mail server, or when you want to use a third-party service to handle email delivery.

Here's an example of how you might configure sendmail to use a smart relay host:

1. Edit your sendmail.cf file (usually located in /etc/sendmail.cf or /etc/mail/sendmail.cf) and add the following lines:

   define(`SMART_HOST', `your-relay-host.example.com')
   define(`RELAY_MAILER_ARGS', `TCP $h 25')

   Replace your-relay-host.example.com with the hostname or IP address of your relay host.

2. Save the changes to your sendmail.cf file and restart the sendmail service.

3. Verify that the relay host is working by sending an email to a recipient outside of your domain. The email should be relayed through the smart relay host.

Some things to keep in mind:

• Make sure the relay host is configured to accept email from your domain.
• Verify that the relay host is not blacklisted or has a poor reputation, as this could impact email delivery.
• Be aware that using a smart relay host can introduce additional latency and potential issues with email delivery.