In case you face some issues with the popular email providers, please check whether you have allowed the usage of the third-party apps. The problem may be in the security limitation and without changing some security settings you may face the incorrect work of the SMTP extension.
The solution for Gmail can be found here. You may find the desired manual for your other email providers in their help sections or seek help via their support teams.
Our SMTP module can be configured to send emails via Yahoo, Gmail or any other third-party SMTP server. Due to a pre-defined data autofill option you will just need to choose a certain SMTP provider, and other fields ('Server Address', "Port", "Connection Security", etc.) will be filled in automatically.