GoDaddy Send Email - asp.net

Question

I am using ASP.Net 4.0 with MVC 3 and C# to try and send an email from my site. This code works on other hosts but for some reason GoDaddy is erroring out. Here is the code I am using.
var fAddress = new MailAddress("customers#email.com");
var tAddress = new MailAddress("mygodaddyaddress#email.com");
var message = new MailMessage(fAddress, tAddress)
{
Subject = subject,
Body = body
};
var client = new SmtpClient("relay-hosting.secureserver.net");
client.Send(message);
Here is the error I am receiving
Mailbox name not allowed. The server response was: sorry, your mail was administratively denied. (#5.7.1)
Any other GoDaddy users here that can shed some light?

Answer 1

It might be something to do with the from address:
Problem seem to be the FROM email address. The FROM email address must be an email address with the hosted domain to avoid this error. For example if you have a hosted domain yourdomain.com, your FROM email address should be something like username#yourdomain.com.
Source:
http://www.cosmocentral.com/2009/01/553-sorry-your-mail-was-administratively-denied/

Answer 2

It could be because neither email address is native to the mail server used by GoDaddy, and thus you'd need to allow relaying. This is just one possibility, I think the best approach would be to contact them directly.

Answer 3

Your From address does not need to be a GoDaddy email. It is the user/password for the domain that must be valid. This is what the Web.config should have:
<system.net>
<mailSettings>
<smtp from="me#test.com">
<network host="smtpout.secureserver.net" port="80" userName="foo#bar.com" password="yourpassword" defaultCredentials="false" />
</smtp>
</mailSettings>
</system.net>
Then you can initialize it in code-behind with this:
var mailclient = new SmtpClient();