To connect your Mailster account, you will need the following:
The Mailster WordPress plugin can be purchased from this URL.
Get the required Data
Log in to your WordPress Dashboard.
Go to Plugins → Add New Plugin.
Install the Mailster plugin.
Connect Mailster with Divi's Email Opt-in module
Open the Email Opt-in module Settings modal window.
Go to the Content Tab → Email Account.
Select the Mailster from the provider's list.
Click on the Add button.
Fill in the following fields:
Name - It can be anything you want. For example, you can use
my-mailster
Click on the Submit button.
Choose the Mailster list you want to use.