c# – SMTP和OAuth 2

System.Net.Mail不支持OAuth或OAuth2.但是,只要您拥有用户的OAuth访问令牌(MailKit没有可以获取OAuth令牌的代码,但是如果拥有OAuth令牌可以使用它),则可以使用 MailKit(注意：仅支持OAuth2) SmtpClient发送消息) .

您需要做的第一件事是遵循Google’s instructions获取您的应用程序的OAuth 2.0凭据.

一旦你这样做,获得访问令牌的最简单的方法是使用Google的Google.Apis.Auth库：

var certificate = new X509Certificate2 (@"C:pathtocertificate.p12","password",X509KeyStorageFlags.Exportable);
var credential = new ServiceAccountCredential (new ServiceAccountCredential
    .Initializer ("your-developer-id@developer.gserviceaccount.com") {
    // Note: other scopes can be found here: https://developers.google.com/gmail/api/auth/scopes
    Scopes = new[] { "https://mail.google.com/" },User = "username@gmail.com"
}.FromCertificate (certificate));

bool result = await credential.RequestAccessTokenAsync (CancellationToken.None);

// Note: result will be true if the access token was received successfully

现在你有一个访问令牌(credential.Token.AccessToken),你可以像MailKit一样使用密码：

using (var client = new SmtpClient ()) {
    client.Connect ("smtp.gmail.com",587,SecureSocketOptions.StartTls);

    // use the access token as the password string
    client.Authenticate ("username@gmail.com",credential.Token.AccessToken);

    client.Send (message);

    client.Disconnect (true);
}