如何将文件附件添加到从Razor页发送的电子邮件中（使用ASP.NET Core和MailKit）

Question

以下是从ASP.NET Core中的Razor页面发送电子邮件的方法。 由于System.Net.Mail在ASP.NET Core中不可用，因此我需要使用MailKit。

尽管进行了大量研究，但我仍无法找到一种将图像包含到电子邮件中的方法。 请注意，它不必一定是附件-嵌入图像即可。

    public ActionResult Contribute([Bind("SubmitterScope, SubmitterLocation, SubmitterItem, SubmitterCategory, SubmitterEmail, SubmitterAcceptsTerms, SubmitterPicture")]
        EmailFormModel model)
    {

        if (ModelState.IsValid)
        {
            try
            {
                var emailName= _appSettings.EmailName;
                var emailAddress = _appSettings.EmailAddress;
                var emailPassword = _appSettings.EmailPassword;

                var message = new MimeMessage();
                message.From.Add(new MailboxAddress(emailName, emailAddress));
                message.To.Add(new MailboxAddress(emailName, emailAddress));
                message.Subject = "Record Submission From: " + model.SubmitterEmail.ToString();
                message.Body = new TextPart("plain")
                {
                    Text = "Scope: " + model.SubmitterScope.ToString() + "\n" +
                        "Zip Code: " + model.SubmitterLocation.ToString() + "\n" +
                        "Item Description: " + model.SubmitterItem.ToString() + "\n" +
                        "Category: " + model.SubmitterCategory + "\n" +
                        "Submitted By: " + model.SubmitterEmail + "\n" +
                        // This is the file that should be attached.
                        //"Picture: " + model.SubmitterPicture + "\n" +
                        "Terms Accepted: " + model.SubmitterAcceptsTerms + "\n"
                };

                using (var client = new SmtpClient())
                {
                    client.Connect("smtp.gmail.com", 587);

                    // Note: since we don't have an OAuth2 token, disable
                    // the XOAUTH2 authentication mechanism.
                    client.AuthenticationMechanisms.Remove("XOAUTH2");

                    // Note: only needed if the SMTP server requires authentication
                    client.Authenticate(emailAddress, emailPassword);

                    client.Send(message);
                    client.Disconnect(true);
                    return RedirectToAction("Success");
                }
            }
            catch (Exception ex)
            {

                Debug.WriteLine(ex.Message + ": " + ex.StackTrace);
                return RedirectToAction("Failure");
            }
        }
        else
        {
            return View();
        }
    }

Answer 1

这来自Mailkit github存储库上的FAQ，似乎涵盖了整个过程。 https://github.com/jstedfast/MailKit/blob/master/FAQ.md#CreateAttachments

var message = new MimeMessage ();
message.From.Add (new MailboxAddress ("Joey", "joey@friends.com"));
message.To.Add (new MailboxAddress ("Alice", "alice@wonderland.com"));
message.Subject = "How you doin?";

// create our message text, just like before (except don't set it as the message.Body)
var body = new TextPart ("plain") {
    Text = @"Hey Alice,

What are you up to this weekend? Monica is throwing one of her parties on
Saturday and I was hoping you could make it.

Will you be my +1?

-- Joey
"
};

// create an image attachment for the file located at path
var attachment = new MimePart ("image", "gif") {
    ContentObject = new ContentObject (File.OpenRead (path), ContentEncoding.Default),
    ContentDisposition = new ContentDisposition (ContentDisposition.Attachment),
    ContentTransferEncoding = ContentEncoding.Base64,
    FileName = Path.GetFileName (path)
};

// now create the multipart/mixed container to hold the message text and the
// image attachment
var multipart = new Multipart ("mixed");
multipart.Add (body);
multipart.Add (attachment);

// now set the multipart/mixed as the message body
message.Body = multipart;