使用 MailKit 发送电子邮件的 dotnet 核心网站中的奇怪问题

Question

我刚从供应商那里继承了一个网站，并检查了该网站的错误和源代码。

该应用程序基于 dotnet core 1.1 构建，并使用 Mailkit 通过我们的公司代理通过 SMTP 发送电子邮件。

问题是邮件发送功能在发送电子邮件时表现不稳定。大多数时候我调试它出错的发送方法。我们使用 Authentication Required Flag 并将 userId 和 Password 传递给 MailKit Authenticate Method

StackTrace 消息

AuthenticationInvalidCredentials: 5.7.3 Authentication unsuccessful

at MailKit.Net.Smtp.SmtpClient.Authenticate(Encoding encoding, ICredentials credentials, CancellationToken cancellationToken) at MailKit.MailService.Authenticate(String userName, String password, CancellationToken cancellationToken) at Rules.Emailer.SendNotification.Send(String to, String from, String subject, String body) in C:\Workspace\G\Rules\Emailer\SendNotification.cs:line 94 at G.Rules.Emailer.UserNotifications.ResetPassword(String

代码片段

using (var client = new SmtpClient())
{
    client.Connect(EmailConfiguration.SmtpServer, EmailConfiguration.SmtpPort, EmailConfiguration.UseSsl);

    if (EmailConfiguration.RequiresAuthentication)
    {
        client.Authenticate(EmailConfiguration.Username, EmailConfiguration.Password);
    }

    //TODO: Only Send if PROD
    client.Send(message);
    client.Disconnect(true);
}

return true;
}

Answer 1

Connected to smtp://<IP>:25/?starttls=when-available
S: 220 <Server_REDACTED>.<DOMAIN_REDACTED>.COM Microsoft ESMTP MAIL Service ready at Tue, 27 Mar 2018 03:22:42 -0400
C: EHLO [10.207.8.74]
S: 250-<Server_REDACTED>.<DOMAIN_REDACTED>.COM Hello [10.207.8.74]
S: 250-SIZE
S: 250-PIPELINING
S: 250-DSN
S: 250-ENHANCEDSTATUSCODES
S: 250-STARTTLS
S: 250-X-ANONYMOUSTLS
S: 250-AUTH NTLM
S: 250-X-EXPS GSSAPI NTLM
S: 250-8BITMIME
S: 250-BINARYMIME
S: 250-CHUNKING
S: 250-XEXCH50
S: 250-XRDST
S: 250 XSHADOW
C: STARTTLS
S: 220 2.0.0 SMTP server ready
C: EHLO [10.207.8.74]
S: 250-<Server_REDACTED>.<DOMAIN_REDACTED>.COM Hello [10.207.8.74]
S: 250-SIZE
S: 250-PIPELINING
S: 250-DSN
S: 250-ENHANCEDSTATUSCODES
S: 250-AUTH NTLM LOGIN
S: 250-X-EXPS GSSAPI NTLM
S: 250-8BITMIME
S: 250-BINARYMIME
S: 250-CHUNKING
S: 250-XEXCH50
S: 250-XRDST
S: 250 XSHADOW
C: AUTH LOGIN
S: 334 VXNlcm5hbWU6
C: <EMAIL_REDACTED>  
S: 334 UGFzc3dvcmQ6
C: <PSWD_REDACTED> 
S: 535 5.7.3 Authentication unsuccessful

Answer 2

NTLM连接，你可以试试：

await client.ConnectAsync(SmtpServer.SenderServer, SmtpServer.Port).ConfigureAwait(false);

if (client.AuthenticationMechanisms.Contains("NTLM"))
{
    var ntlm = new SaslMechanismNtlm(SmtpServer.UserName, SmtpServer.Password);
    await client.AuthenticateAsync(ntlm).ConfigureAwait(false);
}
else
{
    await client.AuthenticateAsync(SmtpServer.UserName, SmtpServer.Password).ConfigureAwait(false);
}

使用 MailKit 发送电子邮件的 dotnet 核心网站中的奇怪问题

Weird Issue in dotnet core website using MailKit to send email

smtp

mailkit

.net-core

.net-core-1.1