Gmail API 创建和发送电子邮件 .NET C#

Question

问题

我正在尝试将 Gmail API 实施到 API 应用程序中。我创建了一个服务帐户并保存了 p12 密钥和 json 凭据。我正在谈论一个失败的先决条件。我认为这可能与我要发送的信息有关。

代码

String serviceAccountEmail = "SERVICE-ACC-EMAIL";
X509Certificate2 certificate = new X509Certificate2("./key.p12", "notasecret", X509KeyStorageFlags.Exportable);
// FileStream stream = new FileStream("./credentials.json", FileMode.Open, FileAccess.Read); // ! Not Used
            
ServiceAccountCredential credential = new ServiceAccountCredential(new ServiceAccountCredential.Initializer(serviceAccountEmail)
{
    User = serviceAccountEmail,
    Scopes = new[] { GmailService.Scope.MailGoogleCom }
}.FromCertificate(certificate));
GmailService service = new GmailService(new BaseClientService.Initializer()
{
    HttpClientInitializer = credential,
    ApplicationName = "Testing Application",
}); 
var result = service.Users.Messages.Send(CreateEmail.CreateEmailMessage(), "me").Execute();

异常

An unhandled exception of type 'Google.GoogleApiException' occurred in System.Private.CoreLib.dll: 'Google.Apis.Requests.RequestError
Precondition check failed. [400]
Errors [
    Message[Precondition check failed.] Location[ - ] Reason[failedPrecondition] Domain[global]
]'

构建邮件消息（不起作用）

在 CreateEmail.CreateEmailMessage 方法中，我构建了一个新的 Google.Apis.Gmail.v1.Data.Message 实例。设置有效负载和标头。以此为参考。我不确定这是否是这样做的方法，但我似乎找不到创建新消息的方法。我只能找到用 Java 或 Python 编写的东西，我尝试将其转换为 C#，但失败了

var msg2 = new Message()
{
    Payload = new MessagePart()
    {
        Body = new MessagePartBody()
        {
            Data = Convert.ToBase64String(Encoding.UTF8.GetBytes("Hello world"))
        },
        Headers = new List<MessagePartHeader>() {
            new MessagePartHeader() { Name = "To", Value = "My email"},
...

Answer 1

前提条件检查失败。 [400]

使用 Gmail api 和服务帐户通常意味着您没有正确设置服务帐户的域范围委派。

Implementing Server-Side Authorization

在您的情况下，这可能是因为您委派给不在您域中的用户。

User = serviceAccountEmail,

不是服务帐户电子邮件地址，而是您希望服务帐户模拟的 Google Workspace 用户。

string ApplicationName = "Gmail API .NET Quickstart";
const string serviceAccount = "clawskeyboard-smtp@clawskeyboard-api.iam.gserviceaccount.com";
    
var certificate = new X509Certificate2(@"D:\api-ed4859a67674.p12", "notasecret", X509KeyStorageFlags.Exportable);
    
var gsuiteUser = "xxx@YourWorkGroupDomain.com";
    
var serviceAccountCredentialInitializer = new ServiceAccountCredential.Initializer(serviceAccount)
                {
                    User = gsuiteUser,
                    Scopes = new[] { GmailService.Scope.GmailSend, GmailService.Scope.GmailLabels }
    
                }.FromCertificate(certificate);