How can I enable DKIM email verification on windows server 2019 for sending DKIM verified email via SMTP service?

Question

I am sending activation and verification emails from my domain : https://www.monstermmorpg.com/

Recently I have moved to a new installation

The new server is : Windows Server 2019

How can I set a proper DKIM?

Moreover, gmail tells that the message is not encrypted

How can I encrypt messages?

I have thoroughly searched the internet and I couldn't find how to send email by SMTP when SSL is enabled

Looking for help thank you

This is my current C# code to send email

            using (MailMessage Email = new MailMessage(new MailAddress("noreply@monstermmorpg.com", srFrom), new MailAddress(srEmailAddress)))
        {
            Email.IsBodyHtml = true;
            Email.SubjectEncoding = Encoding.UTF8;
            Email.BodyEncoding = Encoding.UTF8;
            Email.Subject = srSubject;
            Email.ReplyTo = new MailAddress("admin@monstermmorpg.com", "MonsterMMORPG Administrator");
            using (AlternateView textPart = AlternateView.CreateAlternateViewFromString(srBodyText, Encoding.UTF8, "text/plain"))
            {
                using (AlternateView htmlPart = AlternateView.CreateAlternateViewFromString(srBodyHTML, Encoding.UTF8, "text/html"))
                {
                    textPart.TransferEncoding = System.Net.Mime.TransferEncoding.QuotedPrintable;
                    Email.AlternateViews.Add(textPart);

                    htmlPart.TransferEncoding = System.Net.Mime.TransferEncoding.QuotedPrintable;
                    Email.AlternateViews.Add(htmlPart);

                    using (SmtpClient smtpClient = new SmtpClient("127.0.0.1", 25))
                    {
                        smtpClient.Send(Email);                            
                        return "True";
                    }
                }
            }
        }

The received email source code from gmail

    Delivered-To: monstermmorpg@gmail.com
Received: by 2002:a2e:3217:0:0:0:0:0 with SMTP id y23csp506469ljy;
        Fri, 14 May 2021 09:06:00 -0700 (PDT)
X-Google-Smtp-Source: ABdhPJzjZd6rMp/pnpxKsq1L06bwDvzbj8muKWN6+nFTLZU75Q7umGzQxkkil5RdVKUXcPvQCYe+
X-Received: by 2002:a67:f612:: with SMTP id k18mr36628964vso.14.1621008359976;
        Fri, 14 May 2021 09:05:59 -0700 (PDT)
ARC-Seal: i=1; a=rsa-sha256; t=1621008359; cv=none;
        d=google.com; s=arc-20160816;
        b=MfAvouyS6gARsLUkbkExyiliKm5JTjKiQyJneWOJ+ClrDqYnHYAnOR9+sd5DGHqAHQ
         B1uFRt+e8zPmi9BjiMrlzmU6vbBduXIe5XqpuZln9iUj6p3UvzM5RYwLfLgWru2kiU7L
         4JHw/qL0+u7EU2/7ONHY5OtzU6ky8y2zgHiBC+cymThrA/yrgf248TWxAjQ0kHbKggbD
         EeXPUmBEwZTYAYlI1BfRxeb3vMDd6fxddDuE9H2caU6FHmD2xZ/kqBsVYbAKIlb2kZsn
         wvL8cPoGL8PhoH+zW/SqSzjLdb4lxHqdmucUYlQDOKXhtYOWrmwGbTv5p3U5QvgBG7+R
         +0Qg==
ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816;
        h=message-id:subject:date:reply-to:to:from:mime-version;
        bh=pl1glJA514sUYwdSYbJnqcj6IappZiIhLxbY8IS1skY=;
        b=gMouTK8xFFFUh2FegtyhVHu6EDZetSBQpyXKGTkzekmkQAMyv7GS3id5eC1hpxkOPI
         mMogftz7u7zVWHXxJld5AZwmdXAEyngNSQpRd1ejYPnLLihZ+4vnC25TMOSlDR4XSrV/
         EPfLkTAASP/+nMeNMBOkaZ04BHobfE4YOWaelRDdKJMfsIv/Q7kUlD2+x8sYIP5gYH1A
         IH3nxYIvc1krQhQiFapzplAaLTuw45JU514M2UHwxv48uqZsSo6xvM/66PVL8a4AM9QY
         oMZRFrNZbVs/jHOmfo7NmbhQKspmU6piBeikxXc62gEZrZscTjj1CnF1ExDOBYU4VTaR
         rClA==
ARC-Authentication-Results: i=1; mx.google.com;
       spf=pass (google.com: domain of noreply@monstermmorpg.com designates 198.154.81.18 as permitted sender) smtp.mailfrom=noreply@monstermmorpg.com
Return-Path: <noreply@monstermmorpg.com>
Received: from WIN-NKJ7NU5TC3R ([198.154.81.18])
        by mx.google.com with ESMTP id w2si4313304uau.70.2021.05.14.09.05.59
        for <monstermmorpg@gmail.com>;
        Fri, 14 May 2021 09:05:59 -0700 (PDT)
Received-SPF: pass (google.com: domain of noreply@monstermmorpg.com designates 198.154.81.18 as permitted sender) client-ip=198.154.81.18;
Authentication-Results: mx.google.com;
       spf=pass (google.com: domain of noreply@monstermmorpg.com designates 198.154.81.18 as permitted sender) smtp.mailfrom=noreply@monstermmorpg.com
Received: from WIN-NKJ7NU5TC3R ([127.0.0.1]) by WIN-NKJ7NU5TC3R with Microsoft SMTPSVC(10.0.17763.1697);
     Fri, 14 May 2021 16:05:59 +0000
MIME-Version: 1.0
From: MonsterMMORPG <noreply@monstermmorpg.com>
To: monstermmorpg@gmail.com
Reply-To: MonsterMMORPG Administrator <admin@monstermmorpg.com>
Date: 14 May 2021 16:05:59 +0000
Subject: MonsterMMORPG Email Verification - Account Activation
Content-Type: multipart/alternative; boundary=--boundary_0_1f9b8fcb-6eb3-4f2d-903e-a44c9cf7ecbf
Return-Path: noreply@monstermmorpg.com
Message-ID: <WIN-NKJ7NU5TC3RaJiR00000002@WIN-NKJ7NU5TC3R>
X-OriginalArrivalTime: 14 May 2021 16:05:59.0129 (UTC) FILETIME=[077B7C90:01D748DB]

----boundary_0_1f9b8fcb-6eb3-4f2d-903e-a44c9cf7ecbf
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable

CeFurkan Welcome to MonsterMMORPG

score 2 · Answer 1 · answered May 15 '21 at 06:17

The Received: ... with Microsoft SMTPSVC(10.0.17763.1697); suggests you are using IIS SMTP.

As IIS SMTP is from IIS 6.0 (code name "Duct Tape", included with Windows Server 2003) and not updated since, it does not support DKIM, which has been produced afterwards (released in 2005, first RFC from 2007).
The outboud TLS encryption (which is not a message but a transit encryption!) is feasible through:
1. Internet Information Services (IIS) 6.0 Manager
2. [SMTP Virtual Server #1] Properties
3. Delivery
4. Outbound Security...
5. [x] TLS encryption

However, it would be much better to let a fully functional email server like Microsoft Exchange or Postfix handle both DKIM and TLS. Without the intermediate IIS SMTP, using the SmtpClient Class, you could either send the message unencrypted on a local network or utilize STARTTLS from the SmtpClient.EnableSsl Property:

using (SmtpClient smtpClient = new SmtpClient("smtp.example.com", 25))
{
    smtpClient.EnableSsl = true;
    smtpClient.Send(Email);                            
    return "True";
}

How can I enable DKIM email verification on windows server 2019 for sending DKIM verified email via SMTP service?

1 Answers1