Postfix Configure Multiple ISP Client SMTP Authentication

To configure Postfix to use multiple ISP client SMTP authentication, you can use the sasl_password_maps parameter in the main.cf configuration file.

The sasl_password_maps parameter specifies a lookup table that contains the credentials for each of the ISP clients. The table can be in the form of a text file, a database, or a program that generates the table on-the-fly.

To configure multiple ISP client SMTP authentication, follow these steps:

1. Create a text file that contains the credentials for each of the ISP clients. The file should contain one entry per line, with the format client_name username:password. For example:

isp1.example.com user1:password1
isp2.example.com user2:password2

2. Use the postmap utility to build a lookup database from the text file. For example:

# postmap /etc/postfix/sasl_passwd

This will create a database file named sasl_passwd.db.

3. Add the sasl_password_maps parameter to the main.cf configuration file and specify the path to the database file. For example:

sasl_password_maps = hash:/etc/postfix/sasl_passwd

4. Restart the Postfix service to apply the changes.

It's important to note that this is just one example of how to configure multiple ISP client SMTP authentication in Postfix. There are many other parameters and settings that you can configure to customize the behavior of the server. Consult the Postfix documentation and online resources for more information on how to use multiple ISP client SMTP authentication with Postfix.