我有一个标准的Google Apps帐户。我已通过Google Apps设置了自定义域名。当我使用Gmail界面时，我可以通过Google Apps成功发送和接收电子邮件。但是，我想通过代码发送电子邮件。为了尝试这个，我一直在尝试以下代码：
MailMessage mailMessage = new MailMessage();
mailMessage.To.Add("[email protected]");
mailMessage.Subject = "Test";
mailMessage.Body = "<html><body>This is a test</body></html>";
mailMessage.IsBodyHtml = true;
// Create the credentials to login to the gmail account associated with my custom domain
string sendEmailsFrom = "[email protected]";
string sendEmailsFromPassword = "password";
NetworkCredential cred = new NetworkCredential(sendEmailsFrom, sendEmailsFromPassword);
SmtpClient mailClient = new SmtpClient("smtp.gmail.com", 587);
mailClient.EnableSsl = true;
mailClient.DeliveryMethod = SmtpDeliveryMethod.Network;
mailClient.UseDefaultCredentials = false;
mailClient.Timeout = 20000;
mailClient.Credentials = cred;
mailClient.Send(mailMessage);
到达Send方法时，抛出异常，指出：
“SMTP服务器需要安全连接或客户端未经过身份验证。服务器响应为：5.5.1需要身份验证。”
如何通过Google通过自定义域发送电子邮件？
谢谢！
无需对代码中的所有smtp设置进行硬编码。把它们放在web.config中。这样，您可以根据需要加密这些设置，并在不重新编译应用程序的情况下即时更改它们。
<configuration>
<system.net>
<mailSettings>
<smtp from="[email protected]" deliveryMethod="Network">
<network host="smtp.gmail.com" port="587"
userName="[email protected]" password="password"/>
</smtp>
</mailSettings>
</system.net>
</configuration>
发送电子邮件时结束只需在SmtpClient上启用SSL：
var message = new MailMessage("[email protected]");
// here is an important part:
message.From = new MailAddress("[email protected]", "Mailer");
// it's superfluous part here since from address is defined in .config file
// in my example. But since you don't use .config file, you will need it.
var client = new SmtpClient();
client.EnableSsl = true;
client.Send(message);
确保您从与Gmail尝试进行身份验证的电子邮件地址发送电子邮件。
注意：从.NET 4.0开始，您可以将enableSsl =“true”插入到web.config中，而不是在代码中设置它。
这就是我在WPF 4中使用的内容
SmtpClient client = new SmtpClient();
client.Credentials = new NetworkCredential("[email protected]", "P@$$w0rD");
client.Port = 587;
client.Host = "smtp.gmail.com";
client.EnableSsl = true;
try {
MailAddress
maFrom = new MailAddress("[email protected]", "Sender's Name", Encoding.UTF8),
maTo = new MailAddress("[email protected]", "Recipient's Name", Encoding.UTF8);
MailMessage mmsg = new MailMessage(maFrom.Address, maTo.Address);
mmsg.Body = "<html><body><h1>Some HTML Text for Test as BODY</h1></body></html>";
mmsg.BodyEncoding = Encoding.UTF8;
mmsg.IsBodyHtml = true;
mmsg.Subject = "Some Other Text as Subject";
mmsg.SubjectEncoding = Encoding.UTF8;
client.Send(mmsg);
MessageBox.Show("Done");
} catch (Exception ex) {
MessageBox.Show(ex.ToString(), ex.Message);
//throw;
}
注意防火墙和反病毒。这些令人毛骨悚然的东西往往会阻止发送电子邮我使用McAfee Enterprise，我必须添加可执行文件名（如Bazar.exe和Bazar.vshost.exe的Bazar。*）才能发送电子邮件...
将端口更改为465
没有必要做任何事情。只需首次登录您当前的帐户并按照说明操作即可。
你的问题会解决。之所以出现这种情况，是因为您在Google应用中创建了该帐户但未登录。只需登录并按照说明进行操作即可。
我的代码在Port = 587上使用TLS连接到smtp.google.com（SSL应该是端口465），但仍然需要EnableSsl = true
SmtpClient smtp = new SmtpClient();
smtp.Host = "smtp.gmail.com";
smtp.Port = 587;
smtp.EnableSsl = true;
smtp.UseDefaultCredentials = false;
NetworkCredential credentials = new NetworkCredential();
credentials.UserName = "INSERT EMAIL";
credentials.Password = "INSERT PASSWORD";
smtp.Credentials = credentials;
MailAddress addressFrom = new MailAddress(credentials.UserName);
MailAddress addressTo = new MailAddress("INSERT RECIPIENT");
MailMessage msg = new MailMessage(addressFrom, addressTo);
msg.Subject = "SUBJECT"
msg.Body = "BODY";
smtp.Send(msg);
请注意您的G SUITE帐户中的这些重要先决条件