By default Exim will be using the main server IP to send mails. If the main server IP is listed in any spam database, then we will not be able to send mails. In order to fix this, we can change the Exim mail server IP to any other IP (which is not blacklisted) on the server. To do this follow the steps given below.

1. Open the Exim configuration file

2. Locate the section of the file that contains the following:

3. Replace this section with the following modified version :

You need to substitute the right IP address here.

4. Restart Exim using the following commands

This will change the outgoing mail server IP of the exim mail server.