Sending an email with the email address submitted by the user (using smtp and gmail in asp.net)

Question

I added a page to my website that should send an email to my gmail account once a user submits a message with their email address. I want to set msg.from part of the code to be whatever the user puts in the txtEmail.text section. The html;

<h2>Contact Us</h2>
        <br />
        <table>            
            <tr>
                <td  style="align-items:center">
                    Name:</td>
                <td>
                    <asp:TextBox ID="txtName"
                                    runat="server"
                                    Columns="40"></asp:TextBox>
                </td>
            </tr>
            <tr>
                <td  style="align-items:center">
                    email:</td>
                <td>
                    <asp:TextBox ID="txtEmail"
                                    runat="server"
                                    Columns="40"></asp:TextBox>
                </td>
            </tr>



            <!-- Message -->
            <tr>
                <td style="align-items:center">
                    What are you looking for?
                </td>
                <td>
                    <asp:TextBox ID="txtMessage"
                                    runat="server"
                                    Columns="40"
                                    Rows="6"
                                    TextMode="MultiLine"></asp:TextBox>
                </td>
            </tr>
             <tr>
                <td  style="align-items:center">
                    What would you be willing to pay for this app?</td>
                <td>
                    <asp:TextBox ID="txtPay"
                                    runat="server"
                                    Columns="40"></asp:TextBox>
                </td>
            </tr>

            <!-- Submit -->
            <tr style="align-items:center">
                <td colspan="2">
                    <asp:Button ID="btnSubmit" runat="server" Text="Submit"
                        onclick="btnSubmit_Click" /><br />
                </td>
            </tr>

            <!-- Results -->
            <tr style="align-items:center">
                <td colspan="2">
                    <asp:Label ID="lblResult" runat="server"></asp:Label>
                </td>
            </tr>
        </table>

This is the code behind page;

protected void btnSubmit_Click(object sender, EventArgs e)
    {
        SmtpClient smtpClient = new SmtpClient("smtp.gmail.com", 587);
        smtpClient.UseDefaultCredentials = true;
        smtpClient.DeliveryMethod = SmtpDeliveryMethod.Network;
        smtpClient.EnableSsl = true;


        try
        {
            //Create the msg object to be sent
            MailMessage msg = new MailMessage();
            //Add your email address to the recipients
            msg.To.Add("ronan.byrne@mhlabs.net");

            //Configure the address we are sending the mail from
            msg.From = new MailAddress("info@MyWebsiteDomainName", "MyWeb Site");

            msg.To.Add(new MailAddress("ronan.byrne@mhlabs.net"));
            //Append their name in the beginning of the subject
            msg.Subject = txtName.Text + txtEmail;
            msg.Body = txtMessage.Text;

            //Send the msg
            smtpClient.Send(msg);

            //Display some feedback to the user to let them know it was sent
            lblResult.Text = "Your message was sent!";

            //Clear the form
            txtName.Text = "";
            txtMessage.Text = "";
            txtEmail.Text = "";
            txtPay.Text = "";
            lblResult.Text = "";
        }
        catch
        {
            //If the message failed at some point, let the user know
            lblResult.Text = "Your message failed to send, please try again.";
        }
    }

Answer 1

Change this:

msg.From = new MailAddress("info@MyWebsiteDomainName", "MyWeb Site");

To:

msg.From = new MailAddress(txtEmail.Text, "MyWeb Site");