Question

出了什么问题？

我正在尝试发送电子邮件，但我在问题的标题中收到错误。为什么不将对象转换为'System.Net.Mail.MailMessage'。

    private object message;

    protected void btnSend_Click(object sender, EventArgs e)
    {
        String TMess = txtMessageBody.Text;
        String TEmail = txtEmail.Text;
        String TSub = txtSubject.Text;

        //this particular email server requires us to login so
        //create a set of credentials with the relevent username and password
        System.Net.NetworkCredential userpass = new System.Net.NetworkCredential();
        userpass.UserName = "email";
        userpass.Password = "password";

        //ensure the smtp client has the newly created credentials
        client.Credentials = userpass;

        if (TSub == "")
        {
            System.Windows.Forms.MessageBox.Show("Error: Enter the message.");
        }
        else
        {
            //create a new email from REPLACE_WITH_USER@gmail.com to recipient@domain.com
            MailMessage message = new MailMessage("helloworld@gmail.com", txtEmail.Text);
        }

        //set the subject of the message, and set the body using the text from a text box
        message.Subject = txtSubject.Text;
        message.Body = txtMessageBody.Text;

        //send the message
        client.Send(message);

        //clear the message box
        //the email has been sent - either by displaying a message (e.g. a literal) or by redirecting them to a 'Message sent' page
        txtMessageBody.Text = "";
        txtEmail.Text = "";
        txtSubject.Text = "";


    }

Answer 1

var client = new SmtpClient();
var message = new MailMessage("helloworld@gmail.com", txtEmail.Text);
var subject = txtSubject.Text;
var body = txtMessageBody.Text;
message.Subject = subject;
mail.Body = body;
client.Send(message);

绝对最低限度应该可以正常工作。尝试一次添加一行其他代码，看看它在哪里断开。

Answer 2

问题在于你的if else循环。如果它转到if语句（而不是else语句），则mailmessage对象不存在。不存在的东西无法解析。

you can do it like this
MailMessage message = new MailMessage("helloworld@gmail.com", txtEmail.Text
if (TSub == "")
{
        System.Windows.Forms.MessageBox.Show("Error: Enter the         message.");
        return;
}

无法从'object'转换为'System.Net.Mail.MailMessage'

2 个答案: