How to obtain the available groups

it.mailupnet.services.MailupSend myService = new it.mailupnet.services.MailupSend();
string s1 = myService.LoginFromId(user, password, myConsoleID);
 
...//extract accessKey value
 
string s2 = myService.GetGroups(accessKey, 1);// retrieving the defined groups for list 1
 
... //extract errorCode value from s2
 
if (errorCode == 0)
{
  // Enter here if call was successful
  // Then you can parse received response and extract groups that belong to the specified list
}