c#使用MailKit和GmailOAuth发送邮件

我正在尝试创建一个应用程序,该程序将在客户进行购买时向他们发送电子邮件.我们有自己的GMail帐户,我将使用该帐户发送电子邮件.

我已经设置了我的应用程序,并在Google API控制台中创建了凭据.我在MailKit的GitHub上发现了this question,这似乎很简单,但似乎对我却不起作用.

这是我的代码：

var secrets = new ClientSecrets
{
ClientId = [CLIENTID]
ClientSecret = [SECRET]
};
var googleCredentials = await GoogleWebAuthorizationBroker.AuthorizeAsync(secrets, new[] { GmailService.Scope.MailGoogleCom }, email, CancellationToken.None);
await googleCredentials.RefreshTokenAsync(CancellationToken.None);
using (var client = new SmtpClient())
{
client.Connect("smtp.gmail.com", 587);
var credentials = new NetworkCredential(googleCredentials.UserId, googleCredentials.Token.AccessToken);
client.Authenticate(credentials);
await client.SendAsync(message);
client.Disconnect(true);
}


调用Authenticate会出现以下错误：

MailKit.Security.AuthenticationException :
AuthenticationInvalidCredentials: 5.7.8 Username and Password not

accepted. Learn more at

5.7.8 07001 m3-v6sm3447324wrs.39 – gsmtp

例外情况是Google支持页面仅说明使用两步验证应用密码或启用安全性较低的应用.我什么都不想要.为什么在.NET中如此困难？我之前用node完成过,这非常简单：

var smtp = mailer.createTransport({
service: "Gmail",
auth: {
type: "OAuth2",
user: process.env.EMAIL,
clientId: process.env.CLIENT_ID,
clientSecret: process.env.CLIENT_SECRET,
refreshToken: process.env.REFRESH_TOKEN
}
});


请不要忘记我已经看过this answer,但是我不太了解如何获得Google信任的X509证书.据我所知,在Google文档中没有与此相关的内容.

解决方法:

解决方案是使用SaslMechanismOAuth2而不是NetworkCredential进行身份验证.我现在有以下工作原理：

var secrets = new ClientSecrets
{
ClientId = Environment.GetEnvironmentVariable("GMailClientId"),
ClientSecret = Environment.GetEnvironmentVariable("GMailClientSecret")
};
var googleCredentials = await GoogleWebAuthorizationBroker.AuthorizeAsync(secrets, new[] { GmailService.Scope.MailGoogleCom }, email, CancellationToken.None);
if (googleCredentials.Token.IsExpired(SystemClock.Default))
{
await googleCredentials.RefreshTokenAsync(CancellationToken.None);
}
using (var client = new SmtpClient())
{
client.Connect("smtp.gmail.com", 587, SecureSocketOptions.StartTls);
var oauth2 = new SaslMechanismOAuth2(googleCredentials.UserId, googleCredentials.Token.AccessToken);
client.Authenticate(oauth2);
await client.SendAsync(message);
client.Disconnect(true);
}