Please create the log using the Smtp.DefaultLogWriter property:
Smtp.DefaultLogWriter = new FileLogWriter(@"C:\MyData\log.txt", LogLevel.Debug);
Rebex.Net.Smtp.Send("email@example.com", "firstname.lastname@example.org", "Subject", "Body", "192.168.110.4");
and then either post the log here, or send it to email@example.com. From the log we will be able to see why you are unable to connect ot your SMTP server and help you then.