未在返回语句前等待异步承诺

Question

昨天遇到了这个问题，更改了一些代码，然后又再次发生...为什么两个邮件都不发送？诺言没有等待。有时发送1封邮件，有时发送2封邮件。布尔“ messagesSent”有时也会返回false，而应该返回true。

功能：

private async Task<bool> SendMails(string email, string name, string pdfPath, string imgPath)
{
    var client = new SendGridClient(_config["SendGrid:Key"]);
    bool messagesSent = false;
    try
    {
        var messageClient = new SendGridMessage
        {
            From = new EmailAddress(_config["SendGrid:Recipient"]),
            Subject = "Subject1",
            HtmlContent = _textManager.Get("email-b")
        };

        var MessageServer = new SendGridMessage
        {
            From = new EmailAddress(_config["SendGrid:Recipient"]),
            Subject = "Subject2",
            HtmlContent = _textManager.Get("email-s")
        };

        messageClient.AddTo(email, name);
        MessageServer.AddTo(email, name);

        string[] fileListClient = new string[] { pdfPath };
        string[] FileListServer = new string[] { pdfPath, imgPath };

        foreach (var file in fileListClient)
        {
            var fileInfo = new FileInfo(file);

            if (fileInfo.Exists)
                await messageClient.AddAttachmentAsync(fileInfo.Name, fileInfo.OpenRead());
        }

        foreach (var file in FileListServer)
        {
            var fileInfo = new FileInfo(file);

            if (fileInfo.Exists)
                await MessageServer.AddAttachmentAsync(fileInfo.Name, fileInfo.OpenRead());
        }

        var responseClient = await client.SendEmailAsync(messageClient);
        var responseServer = await client.SendEmailAsync(MessageServer);

        if (responseClient.StatusCode.ToString() == "202" && responseServer.StatusCode.ToString() == "202")
        {
            messagesSent = true;
        }
    }
    catch (Exception e)
    {
        Console.WriteLine(e);
    }
    return messagesSent;
}

呼叫者：

                bool sentMails = await SendMails(formCollection["email"], formCollection["name"], pdfPath, imgPath);

                if (!sentMails)
                {
                    errorMessage = "Error sending mails.";
                    succes = false;
                }

编辑：请求有效，呼叫已被ISP / MailServer阻止。这与错误的异步无关。

Answer 1

确定，这是异步调用的全部目的，不是要“等待”或延迟性能。该方法将“运行”。除非该方法中引发异常，否则没有什么可以阻止该方法无法成功执行。

尝试添加一个断点，看看有时messageSent返回false的原因，我怀疑这行：

if (responseClient.StatusCode.ToString() == "202" && responseServer.StatusCode.ToString() == "202")

StatusCode是否也有可能返回“ 200”？