Hi, if you have an external SMTP available, after setting the parameters on main Newsletter setting, use the test button and try to report me the kind of error you have. Sometime a provider must be asked to open a specific port to connect to external SMTPs. If you are on GoDaddy, instead, there are no solutions.
To use mailjet, just set their SMTP parameters and the plugin should work with them.
Let me know, Stefano.
