Emailing from monodevelop .vs. VS2013 - mono

Question

I am attempting to email a small report once a larger process is done running. The email code runs fine under windows 8.1 from VS2013, however when i move the code over to mono under Ubuntu(13.10) it gives the error --
ERROR 535 5.7.8 Error: Authentication failed: UGFzc3dvcmQ6
-- What's puzzling to me is that if there is an Authentication failure under ubuntu/linux shouldn't the same Authentication failure be occurring under windows 8.1. The email server is one which my company runs(not gmail.com/live.com/etc). Any help would be great, thanks in advance.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net.Mail;
using System.Net;
using System.Security.Cryptography.X509Certificates;
using System.Net.Security;
using S22.Imap;
using S22;
namespace testing_email {
class Program {
static void Main(string[] args) {
SmtpClient client = new SmtpClient("mail.XXXXXX.com");
client.DeliveryMethod = SmtpDeliveryMethod.Network;
client.UseDefaultCredentials = false;
client.Credentials = new System.Net.NetworkCredential("myreportuser#XXXXX.com", "password");
client.Port = 25;
client.EnableSsl = true;
MailMessage mailit = new MailMessage();
mailit.Body = "Body body body";
mailit.Subject = "Testing Subject";
mailit.IsBodyHtml = true;
mailit.From = new MailAddress("myreportuser#XXXXXX.com");
mailit.To.Add("l.send.it#XXXXX.com");
try {
ServicePointManager.ServerCertificateValidationCallback = delegate(object s, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors) { return true; };
client.Send(mailit);
Console.WriteLine("Message sent");
Console.ReadLine();
}
catch (Exception ex) {
Console.WriteLine("ERROR " + ex.Message);
Console.ReadLine();
}
}
}
}