Sending email with ASP .NET

[WillR]

Hi, I am trying to produce at a nice simple "contact us" form using the ASP .NET 2 namespace "System.Net.Mail" to send the mail. See C# code snippet below:
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SmtpClient smtpClient = new SmtpClient();
MailMessage objMail = new MailMessage();

MailAddress objMail_fromaddress = new MailAddress(txtFrom.Text);
MailAddress objMail_toaddress = new MailAddress(txtTo.Text);

objMail.From = objMail_fromaddress;
objMail.To.Add(objMail_toaddress);

objMail.Subject = "Web Site Enquiry";

objMail.Body = "Name: " + txtName.Text + "\r\n" +
"Address: " + txtAddress.Text + "\r\n" +
"Message: " + txtComments.Text;

objMail.Priority = MailPriority.Normal;
smtpClient.Host = "mail.mydomain.co.uk";
smtpClient.Credentials = new System.Net.NetworkCredential("username@mydomain.co .uk","Password");

smtpClient.Send(objMail);

etc...
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I have 2 questions:

1. Am I correct in setting the smtpClient Host property to "mail.mydomain.co.uk"? The site is going to be hosted on Cherry

2. Do I need to specify the smtp.Credentials property? I have sent a test email successfully without setting this property, so I'm a bit unsure about the security aspect here.

I'd be grateful for advice from the experts. Cheers, Will

[paulredpath]

Will,

Please use the smtp server 'guava.catalyst2.com', you don't need any credentials and make sure that the from address on the email is @yourdomainhostedwithus. Everything should go smoothly then

[WillR]

Paul, Thanks for the reply. My aim to allow a prospective customer to send an email to the site owner/sales person.

I include a text field on the Web form for the customer email address and then use this value as the email "From" address as below:

MailAddress objMail_fromaddress = new MailAddress(txtFrom.Text);

The enquiry email would need to go to a domain account, i.e. sales@mydomain.co.uk, so I hard-code this as below:

MailAddress objMail_toaddress = new MailAddress("sales@mydomain.co.uk");

However, on your reply you mention that I need to "make sure that the from address on the email is @yourdomainhostedwithus". Is this correct? I thought this would be the customer's address, as above?

Apologies if I'm being dim here...

Thanks, Will

[WhiskyFudge]

Paul is mistaken, as long as one of the address's associated with the email is catalyst2 hosted the email can be sent using guava without the use of any credentials.