sending emails from localhost and online asp.net

I know how to send email through smtp in code in c#

if i set a gmail smtp it works fine in localhost
but when i upload and make it online then gmail (smtp.gmail.com) settings dont work. i have to change settings everytime to (relay-hosting.secureserver.net) at godaddy after uploading

Now my question is! Is there any way i can find out if im on localhost in code or online then change the settings dynamically im storing my settings in db
my working code is

mm.LoadByPrimaryKey(4);//get body , subject etc from db
   mc.LoadByPrimaryKey(1);// get settings from db (host, from , port etc)
 
  var maTo = new MailAddress(strEmail, userName);
     var mMailMessage = new MailMessage
                            {
   Subject = mm.Subject,
   Body = strBody,
   IsBodyHtml = true,
   Priority = MailPriority.High,
   From =new MailAddress(mc.AdminEmailAddress),
   DeliveryNotificationOptions=      DeliveryNotificationOptions.OnFailure
                            };
     mMailMessage.To.Add(maTo);
     var mSmtpClient = new SmtpClient
                                  {
              UseDefaultCredentials = false,
              Host = mc.Host,
              Credentials = CredentialCache.DefaultNetworkCredentials,
              DeliveryMethod = SmtpDeliveryMethod.Network};
              mSmtpClient.Send(mMailMessage);
 

i dont want to change my settings everytime, wether im online or developing in localhost environment

i want this flow and how do i know my application is online or localhost in code behind

if(myconnection ==localhost) then fetch gmail credentials 
 else if (myconnection==online) then fetch godaddys credentials 
 

---