Hi, thank you for sharing your experience, it is important to us to improve our plugin.
Of course, as you can understand, we cannot grant to respond to requests just in a few hours: the plugin is free, the support is free, and we did our best to provide documentation to solve the common problems a user can face.
In your case, the problem could be the delivery speed setting and the failed test could be connected to your provider since Newsletter just “sends” emails, but the delivery, as for every plugin, is provided by external systems (your provider, and SMTP service if you integrated the blog with one and so on). Yes, those are technical problems and we tried to cover them as better as possible, not every situation can be managed, though.
Stefano.
