在C#中生成HTML电子邮件正文

Question

是否有更好的方法在C#中生成HTML电子邮件(通过System.Net.Mail发送),而不是使用Stringbuilder执行以下操作:

string userName = "John Doe";
StringBuilder mailBody = new StringBuilder();
mailBody.AppendFormat("<h1>Heading Here</h1>");
mailBody.AppendFormat("Dear {0}," userName);
mailBody.AppendFormat("<br />");
mailBody.AppendFormat("<p>First part of the email body goes here</p>");

等等等等？

Answer 1

您可以使用MailDefinition类.

这是你如何使用它:

MailDefinition md = new MailDefinition();
md.From = "test@domain.com";
md.IsBodyHtml = true;
md.Subject = "Test of MailDefinition";

ListDictionary replacements = new ListDictionary();
replacements.Add("{name}", "Martin");
replacements.Add("{country}", "Denmark");

string body = "<div>Hello {name} You're from {country}.</div>";

MailMessage msg = md.CreateMailMessage("you@anywhere.com", replacements, body, new System.Web.UI.Control());

另外,我写了一篇关于如何使用MailDefinition类使用模板在C#中生成HTML电子邮件正文的博文.

Answer 2

使用System.Web.UI.HtmlTextWriter类.

StringWriter writer = new StringWriter();
HtmlTextWriter html = new HtmlTextWriter(writer);

html.RenderBeginTag(HtmlTextWriterTag.H1);
html.WriteEncodedText("Heading Here");
html.RenderEndTag();
html.WriteEncodedText(String.Format("Dear {0}", userName));
html.WriteBreak();
html.RenderBeginTag(HtmlTextWriterTag.P);
html.WriteEncodedText("First part of the email body goes here");
html.RenderEndTag();
html.Flush();

string htmlString = writer.ToString();

对于包含样式属性创建的广泛HTML,HtmlTextWriter可能是最好的方法.然而,它可能有点笨拙使用和一些开发人员喜欢标记本身很容易阅读,但是经常HtmlTextWriter关于缩进的选择有点奇怪.

在这个例子中,您还可以非常有效地使用XmlTextWriter: -

writer = new StringWriter();
XmlTextWriter xml = new XmlTextWriter(writer);
xml.Formatting = Formatting.Indented;
xml.WriteElementString("h1", "Heading Here");
xml.WriteString(String.Format("Dear {0}", userName));
xml.WriteStartElement("br");
xml.WriteEndElement();
xml.WriteElementString("p", "First part of the email body goes here");
xml.Flush();

Answer 3

更新答案:

SmtpClient本答案中使用的类的文档现在显示为"过时("SmtpClient及其类型网络设计不佳,我们强烈建议您使用https://github.com/jstedfast/MailKit和https:// github .com/jstedfast/MimeKit代替")'.

资料来源:https://www.infoq.com/news/2017/04/MailKit-MimeKit-Official

原答案:

使用MailDefinition类是错误的方法.是的,它很方便,但它也很原始,依赖于Web UI控件 - 这对于通常是服务器端任务的东西没有意义.

下面介绍的方法基于MSDN文档和Qureshi在CodeProject.com上的帖子.

注意:此示例从嵌入资源中提取HTML文件,图像和附件,但使用其他替代方法获取这些元素的流很好,例如硬编码字符串,本地文件等.

Stream htmlStream = null;
Stream imageStream = null;
Stream fileStream = null;
try
{
    // Create the message.
    var from = new MailAddress(FROM_EMAIL, FROM_NAME);
    var to = new MailAddress(TO_EMAIL, TO_NAME);
    var msg = new MailMessage(from, to);
    msg.Subject = SUBJECT;
    msg.SubjectEncoding = Encoding.UTF8;
 
    // Get the HTML from an embedded resource.
    var assembly = Assembly.GetExecutingAssembly();
    htmlStream = assembly.GetManifestResourceStream(HTML_RESOURCE_PATH);
 
    // Perform replacements on the HTML file (if you're using it as a template).
    var reader = new StreamReader(htmlStream);
    var body = reader
        .ReadToEnd()
        .Replace("%TEMPLATE_TOKEN1%", TOKEN1_VALUE)
        .Replace("%TEMPLATE_TOKEN2%", TOKEN2_VALUE); // and so on...
 
    // Create an alternate view and add it to the email.
    var altView = AlternateView.CreateAlternateViewFromString(body, null, MediaTypeNames.Text.Html);
    msg.AlternateViews.Add(altView);
 
    // Get the image from an embedded resource. The <img> tag in the HTML is:
    //     <img src="pid:IMAGE.PNG">
    imageStream = assembly.GetManifestResourceStream(IMAGE_RESOURCE_PATH);
    var linkedImage = new LinkedResource(imageStream, "image/png");
    linkedImage.ContentId = "IMAGE.PNG";
    altView.LinkedResources.Add(linkedImage);
 
    // Get the attachment from an embedded resource.
    fileStream = assembly.GetManifestResourceStream(FILE_RESOURCE_PATH);
    var file = new Attachment(fileStream, MediaTypeNames.Application.Pdf);
    file.Name = "FILE.PDF";
    msg.Attachments.Add(file);
 
    // Send the email
    var client = new SmtpClient(...);
    client.Credentials = new NetworkCredential(...);
    client.Send(msg);
}
finally
{
    if (fileStream != null) fileStream.Dispose();
    if (imageStream != null) imageStream.Dispose();
    if (htmlStream != null) htmlStream.Dispose();
}

Answer 4

我使用dotLiquid来完成这个任务。

它需要一个模板，并用匿名对象的内容填充特殊标识符。

//define template
String templateSource = "<h1>{{Heading}}</h1>Dear {{UserName}},<br/><p>First part of the email body goes here");
Template bodyTemplate = Template.Parse(templateSource); // Parses and compiles the template source

//Create DTO for the renderer
var bodyDto = new {
    Heading = "Heading Here",
    UserName = userName
};
String bodyText = bodyTemplate.Render(Hash.FromAnonymousObject(bodyDto));

它也适用于集合，请参阅一些在线示例。

Answer 5

我建议使用某种模板。有各种不同的方法来解决这个问题，但本质上是在某个地方（在磁盘上，在数据库中等）保存电子邮件的模板，然后简单地将关键数据（即：收件人姓名等）插入模板中。

这更加灵活，因为这意味着您可以根据需要更改模板而无需更改代码。根据我的经验，您可能会收到来自最终用户的更改模板的请求。如果你想全力以赴，你可以包括一个模板编辑器。

Answer 6

作为 MailDefinition 的替代方案，请查看 RazorEngine https://github.com/Antaris/RazorEngine。

这看起来是一个更好的解决方案。

归因于...

如何使用电子邮件模板c#发送电子邮件

例如

using RazorEngine;
using RazorEngine.Templating;
using System;

namespace RazorEngineTest
{
    class Program
    {
        static void Main(string[] args)
        {
    string template =
    @"<h1>Heading Here</h1>
Dear @Model.UserName,
<br />
<p>First part of the email body goes here</p>";

    const string templateKey = "tpl";

    // Better to compile once
    Engine.Razor.AddTemplate(templateKey, template);
    Engine.Razor.Compile(templateKey);

    // Run is quicker than compile and run
    string output = Engine.Razor.Run(
        templateKey, 
        model: new
        {
            UserName = "Fred"
        });

    Console.WriteLine(output);
        }
    }
}

哪个输出...

<h1>Heading Here</h1>
Dear Fred,
<br />
<p>First part of the email body goes here</p>

前往这里

亲爱的弗雷德，

电子邮件正文的第一部分位于此处