it.mailupnet.services.MailupSend myService = new it.mailupnet.services.MailupSend();
... // perform login by means of LoginFromId(user, password, myConsoleID) method and obtain accessKey value
string s = myService.GetNewsletters(accessKey, 1); //Returns all that have been messages created within list 1
...//extract errorCode value from received response;
if (errorCode == 0)
{
// enter here if request was successful
// then received response can be parsed to retrieve the messages that belong to specified list
}