我可以使用 MailKit 通过电子邮件发送文件吗？

Question

如题，MailKit是否支持发送文件？
如果是，我该怎么做？

Answer 1

是的。这在文档以及FAQ 中进行了解释。

来自常见问题解答：

如何创建带有附件的消息？

要构造带有附件的消息，您需要做的第一件事是创建一个multipart/mixed 容器，然后您需要首先将消息正文添加到该容器中。添加正文后，您可以向其中添加包含您要附加​​的文件内容的 MIME 部分，确保将 Content-Disposition 标头值设置为附件。您可能还想在Content-Disposition 标头上设置filename 参数以及在Content-Type 标头上设置name 参数。最方便的方法是简单地使用 MimePart.FileName 属性 将为您设置这两个参数，并将 Content-Disposition 标头值设置为 attachment（如果尚未设置为其他值）。

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. 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") {
    Content = new MimeContent (File.OpenRead (path)),
    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;

构造带有附件的消息的一种更简单的方法是利用 BodyBuilder类。

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?";

var builder = new BodyBuilder ();

// Set the plain-text version of the message text
builder.TextBody = @"Hey Alice,

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

Will you be my +1?

-- Joey
";

// We may also want to attach a calendar event for Monica's party...
builder.Attachments.Add (@"C:\Users\Joey\Documents\party.ics");

// Now we just need to set the message body and we're done
message.Body = builder.ToMessageBody ();

有关详细信息，请参阅Creating Messages。

Answer 2

@jstedfast 带来了非常酷的解决方案，这里有几个简单的方法示例，可以将文件作为附件发送（在这种情况下是 pdf 文档，但可以应用于任何文件类型）。

var message = new MimeMessage();
// add from, to, subject and other needed properties to your message

var builder = new BodyBuilder();
builder.HtmlBody = htmlContent;
builder.TextBody = textContent;

// you can either create MimeEntity object(s)
// this might get handy in case you want to pass multiple attachments from somewhere else
byte[] myFileAsByteArray = LoadMyFileAsByteArray();
var attachments = new List<MimeEntity>
{
    // from file
    MimeEntity.Load("myFile.pdf"),
    // file from stream
    MimeEntity.Load(new MemoryStream(myFileAsByteArray)),
    // from stream with a content type defined
    MimeEntity.Load(new ContentType("application", "pdf"), new MemoryStream(myFileAsByteArray))
}

// or add file directly - there are a few more overloads to this
builder.Attachments.Add("myFile.pdf");
builder.Attachments.Add("myFile.pdf", myFileAsByteArray);
builder.Attachments.Add("myFile.pdf", myFileAsByteArray , new ContentType("application", "pdf"));

// append previously created attachments
foreach (var attachment in attachments)
{
    builder.Attachments.Add(attachment);
}

message.Body = builder.ToMessageBody();

希望对你有帮助。

Answer 3

您也可以直接使用这种方法发送多个文件。 **注意：这里使用的文件是 IEnumerable 文件**

        try
        {
            var message = new MimeMessage();
            message.From.Add(new MailboxAddress(emailService.FromFullName, emailService.FromEmail));
            message.To.AddRange(emailsToSend.Select(x => new MailboxAddress(x)));
            message.Subject = subject;

            var builder = new BodyBuilder();
            builder.HtmlBody = body;

            foreach (var attachment in files)
            {
                if (attachment.Length > 0)
                {
                    string fileName = Path.GetFileName(attachment.FileName);
                    builder.Attachments.Add(fileName, attachment.OpenReadStream());
                }
            }
            message.Body = builder.ToMessageBody();
           
            }