Hi, great to hear that the plugin works well 
Which node are you using to send emails?
if you are using the SendEmail or SendEmail (Email Details Object) nodes then I guess it wouldn’t work as you can only select the three default email services (SMTP servers) Gmail, Outlook and Yahoo. Since the last update, I added a new SendEmail (Custom SMTP Server) which allows specifying any SMTP server. You should be able to do what you described using that node.
If you are already using that node then I will have to look into it as maybe there is something else that needs to be done.