我试图通过gmail服务器发送邮件，但它给出了一些错误。我已经停用2步验证。
发送时会出现以下错误。
while sending it gives following error.
The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required. Learn more at
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我有什么尝试过：
---------------。aspx page ---------- -
<％@ Page Language =C＃AutoEventWireup =trueCodeBehind =Gmail.aspx.csInherits =FriendsEntreprises.Gmail％> ;
<！DOCTYPE html>
< html xmlns =http：// www .w3.org / 1999 / xhtml>
< head runat =server>
< title>< / title>
< / head>
< body>
< form id =form1runat =server>
----------
What I have tried:
---------------.aspx page-----------
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Gmail.aspx.cs" Inherits="FriendsEntreprises.Gmail" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
发送电子邮件
< asp：Label ID =lblStatusrunat =服务器/>
来自：
< asp：TextBox ID =txtFromrunat =serverWidth =300>
密码：
< asp：TextBox ID =txtPasswordrunat =serverWidth =300TextMode =Password>
收件人：
< asp：TextBox ID =txtTorunat =serverWidth =300> b $ b
主题：
< asp：TextBox ID = txtSubjectrunat =serverWidth =300>
消息：
< asp：TextBox ID =txtMessagerunat =serverTextMode =MultiLineRows =5Columns =100>
< asp：按钮ID =btnSendrunat =serverText =发送OnClick =btnSend_Click/>
Sending Email
<asp:Label ID="lblStatus" runat="server" />
From:
<asp:TextBox ID="txtFrom" runat="server" Width="300">
Password:
<asp:TextBox ID="txtPassword" runat="server" Width="300" TextMode="Password">
To:
<asp:TextBox ID="txtTo" runat="server" Width="300">
Subject:
<asp:TextBox ID="txtSubject" runat="server" Width="300">
Message:
<asp:TextBox ID="txtMessage" runat="server" TextMode="MultiLine" Rows="5" Columns="100">
<asp:Button ID="btnSend" runat="server" Text="Send" OnClick="btnSend_Click" />
< / form>
< / body>
< / html>
-------------------- aspx.cs -------------------
使用System;
使用System.Net.Mail;
名称空间FriendsEntreprises
{
公共部分类Gmail：System.Web.UI.Page
{
protected void Page_Load（object sender，EventArgs e）
{
txtFrom.Focus（）;
}
protected void btnSend_Click（object sender，EventArgs e）
{
try
{
MailMessage objMailMessage = new MailMessage（）;
objMailMessage.From = new MailAddress（txtFrom.Text.Trim（））;
objMailMessage.To.Add（new MailAddress（txtTo.Text.Trim（）））;
objMailMessage.Subject = txtSubject.Text.Trim（）;
objMailMessage。 Body = txtMessage.Text.Trim（）;
objMailMessage.IsBodyHtml = false;
objMailMessage.Priority = MailPriority.High;
System.Net.NetworkCredential objNetworkCredential = new System.Net.NetworkCredential（txtFrom.Text.Trim（），txtPassword.Text.Trim（））;
SmtpClient objSmtpClient = new SmtpClient（）;
objSmtpClient.DeliveryMethod = SmtpDeliveryMethod.Network;
objSmtpClient.Host =smtp.gmail。 com;
objSmtpClient.Port = 587;
objSmtpClient.Credentials = objNetworkCredential;
objSmtpClient.Send（objMailMessage）;
lblStatus.Text =电子邮件已成功发送!! ！;
}
catch（SmtpException ex）
{
lblStatus.ForeColor = System.Drawing.Color.Red;
lblStatus.Text =错误oc在发送消息时治愈了。 + ex.Message;
}
}
}
}
</form>
</body>
</html>
--------------------aspx.cs-------------------
using System;
using System.Net.Mail;
namespace FriendsEntreprises
{
public partial class Gmail : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
txtFrom.Focus();
}
protected void btnSend_Click(object sender, EventArgs e)
{
try
{
MailMessage objMailMessage = new MailMessage();
objMailMessage.From = new MailAddress(txtFrom.Text.Trim());
objMailMessage.To.Add(new MailAddress(txtTo.Text.Trim()));
objMailMessage.Subject = txtSubject.Text.Trim();
objMailMessage.Body = txtMessage.Text.Trim();
objMailMessage.IsBodyHtml = false;
objMailMessage.Priority = MailPriority.High;
System.Net.NetworkCredential objNetworkCredential = new System.Net.NetworkCredential(txtFrom.Text.Trim(), txtPassword.Text.Trim());
SmtpClient objSmtpClient = new SmtpClient();
objSmtpClient.DeliveryMethod = SmtpDeliveryMethod.Network;
objSmtpClient.Host = "smtp.gmail.com";
objSmtpClient.Port = 587;
objSmtpClient.Credentials = objNetworkCredential;
objSmtpClient.Send(objMailMessage);
lblStatus.Text = "Email has been sent successfully!!!";
}
catch (SmtpException ex)
{
lblStatus.ForeColor = System.Drawing.Color.Red;
lblStatus.Text = "Error occured while sending your message." + ex.Message;
}
}
}
}