GD Mail Queue Pro plugin has support for custom SMTP services for PHPMailer. One of the services included is for the SendInBlue email sending service. And, to start using this service to send emails using SMTP you need SendPulse account. After you have set up your SendPulse account, you need to get SMTP access information to add to the GD Mail Queue Pro plugin SendPulse Service settings panel.
To get the required information, open your SendPulse account, click on SMTP tab on top of the page, open SMTP Settings, then open General, and there you will see login (username) and password.