C#

string cServername = "[server]";

System.Management.ConnectionOptions objconn = new System.Management.ConnectionOptions();
            objconn.Impersonation = System.Management.ImpersonationLevel.Impersonate;
            objconn.EnablePrivileges = true;
            objconn.Username = "[user]";
            objconn.Password = "[pass]";
            objconn.Authority = "ntlmdomain:[domain]"; 
            
            
            System.Management.ManagementScope exmangescope = new System.Management.ManagementScope(@"\\" + cServername + @"\root\MicrosoftExchangeV2", objconn);
            System.Management.ObjectQuery objquery = new System.Management.ObjectQuery("SELECT * FROM Exchange_Mailbox");
            System.Management.ManagementObjectSearcher objsearch = new System.Management.ManagementObjectSearcher(exmangescope, objquery);
            System.Management.ManagementObjectCollection queryCollection1 = objsearch.Get();
            string strDisplay;
            foreach (System.Management.ManagementObject instmailbox in queryCollection1)
            {
                strDisplay = instmailbox["MailboxDisplayName"].ToString() + " " + instmailbox["size"].ToString();
                System.Console.WriteLine(strDisplay);
            }