将图像嵌入到System.Web.Mail.MailMessage中的电子邮件中

时间：2016-05-16 07:34:30

标签： c# email

我想使用System.Web.Mail.MailMessage和System.Web.Mail.SmtpMail类发送电子邮件。 我知道这是一个弃用的类，但使用System.Net.Mail对我来说不是一个选项。

到目前为止，我能够发送html格式的邮件，但在发送时我无法将图片嵌入到我的电子邮件中。

这是我到目前为止所尝试过的; 

private static void SendMailMethod(string mailServer, int mailServerPort, string userName, string password)
    {
        const string SMTP_SERVER = "http://schemas.microsoft.com/cdo/configuration/smtpserver";
        const string SMTP_SERVER_PORT =
            "http://schemas.microsoft.com/cdo/configuration/smtpserverport";

        const string SEND_USING = "http://schemas.microsoft.com/cdo/configuration/sendusing";

        const string SMTP_USE_SSL = "http://schemas.microsoft.com/cdo/configuration/smtpusessl";


        const string SMTP_AUTHENTICATE =
           "http://schemas.microsoft.com/cdo/configuration/smtpauthenticate";


        const string SEND_USERNAME =
            "http://schemas.microsoft.com/cdo/configuration/sendusername";
        const string SEND_PASSWORD =
            "http://schemas.microsoft.com/cdo/configuration/sendpassword";


        var mailMessage = new System.Web.Mail.MailMessage();

        mailMessage.Fields[SMTP_SERVER] = mailServer;
        mailMessage.Fields[SMTP_SERVER_PORT] = mailServerPort;
        mailMessage.Fields[SEND_USING] = 2;
        mailMessage.Fields[SMTP_USE_SSL] = false;
        mailMessage.Fields[SMTP_AUTHENTICATE] = 0;
        mailMessage.Fields[SEND_USERNAME] = userName;
        mailMessage.Fields[SEND_PASSWORD] = password;

        mailMessage.From = "abc@xyz.com";
        mailMessage.To = "abc@xyz.com";
        mailMessage.Subject = "Test mail:";
        mailMessage.BodyFormat = MailFormat.Html;

        var mailAttachment = new MailAttachment("E:\\imageToEmbed.jpg");
        mailMessage.Attachments.Add(mailAttachment);
        mailMessage.Attachments.Add(new MailAttachment("E:\\TestAttachmentFile.txt"));

        var htmlBody =
            "<!DOCTYPE html PUBLIC \" -//W3C//DTD XHTML 1.0 Transitional//EN\" \"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd\">" +
            "<html xmlns = \"http://www.w3.org/1999/xhtml\" >" +
            " <head >" +
            "<meta http - equiv = \"content-type\" content = \"text/html; charset=UTF-8\" />" +
            "</head >" +
            "<body style = \"font-family: Segoe UI; text-align:left;\" >" +
            "Following is an embedded image:" +
            "<br />" +
            "<img alt = \"\" src = \"imageToEmbed.jpg\" />" +
            "</body >" +
            "</html >";

        mailMessage.Body = htmlBody;

        try
        {
            SmtpMail.Send(mailMessage);

            Console.WriteLine("Mail sent");
        }
        catch (Exception ex)
        {
            Console.WriteLine("Error:" + ex.ToString());
            throw ex;
        }
    }

此代码发送电子邮件，但邮件显示的是带有十字形的小方块，而不是显示图像。 如何将此“imageToEmbed.jpg”嵌入到我的电子邮件中。

2 个答案:

答案 0 :(得分：2)

使用类System.Web.Mail.Message无法实现这一点，因为该实现抽象了对基础Collaboration Data Objects component的许多功能的访问。

您最好切换到直接使用CDO COM对象，而不是使用Microsoft CDO for Windows 2000 Library提供的包装器。在参考对话框的COM选项卡中添加对var cdo = new CDO.Message(); // configuration var cfg = cdo.Configuration; cfg.Fields[SMTP_SERVER].Value = "smtp.server.com"; cfg.Fields[SMTP_SERVER_PORT].Value = 22; cfg.Fields[SEND_USING].Value = 2; cfg.Fields[SMTP_USE_SSL].Value = true; cfg.Fields[SMTP_AUTHENTICATE].Value = 1; cfg.Fields[SEND_USERNAME].Value = "user@example.com"; cfg.Fields[SEND_PASSWORD].Value = "password"; cfg.Fields.Update(); cdo.To = "awesome@example.com"; cdo.Sender = "me@example.com"; // attachment var cdoatt = cdo.AddAttachment("file:///E:/imageToEmbed.jpg"); //this is why System.Web.Mail can't embed images cdoatt.Fields["urn:schemas:mailheader:content-id"].Value = Guid.NewGuid().ToString("N"); cdoatt.Fields.Update(); // get a reference to out content-id field var cid = cdoatt.Fields["urn:schemas:mailheader:content-id"]; // notice the special layout of SRC on the image tag, //it will be somethong like CID:123456789abcdef cdo.HTMLBody = @"<HTML><BODY><B>CDO</B><BR /> <IMG SRC=""cid:" + cid.Value + @"""/></BODY></HTML>"; cdo.Send(); 的引用。

之后，您可以使用以下代码创建并发送带有嵌入图像的html电子邮件：

MIME-Version: 1.0
Content-Type: multipart/mixed;
    boundary="----=_NextPart_000_0001_01D1AF72.C8AE8C70"
Content-Transfer-Encoding: 7bit
X-Mailer: Microsoft CDO for Windows 2000
Content-Class: urn:content-classes:message
Importance: normal
Priority: normal
X-MimeOLE: Produced By Microsoft MimeOLE V10.0.10011.16384

This is a multi-part message in MIME format.

------=_NextPart_000_0001_01D1AF72.C8AE8C70
Content-Type: multipart/alternative;
    boundary="----=_NextPart_001_0002_01D1AF72.C8AE8C70"


------=_NextPart_001_0002_01D1AF72.C8AE8C70
Content-Type: text/plain;
    charset="iso-8859-1"
Content-Transfer-Encoding: 7bit

plain cdo 

------=_NextPart_001_0002_01D1AF72.C8AE8C70
Content-Type: text/html;
    charset="iso-8859-1"
Content-Transfer-Encoding: 7bit

<HTML><BODY><B>plain cdo</B> <IMG SRC="cid:42"/></BODY></HTML>
------=_NextPart_001_0002_01D1AF72.C8AE8C70--

------=_NextPart_000_0001_01D1AF72.C8AE8C70
Content-Type: image/png;
    name="file.png"
Content-Transfer-Encoding: base64
Content-ID: <42>
Content-Disposition: attachment;
    filename="file.png"

iVBORw0KGgoAAAANSUhEUgAAADQAAABLCAMA

请注意如何在附件上设置Content-ID标头。这是必需的，因此您可以在图像的SRC属性中使用Content-ID。

典型的邮件消息会显示

System.Web.Mail

注意Content-ID（此处为42）。

使用普通MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_NextPart_000_0000_01D1AF70.59FC25F0" X-Mailer: Microsoft CDO for Windows 2000 Content-Class: urn:content-classes:message Importance: normal Priority: normal X-MimeOLE: Produced By Microsoft MimeOLE V10.0.10011.16384 This is a multi-part message in MIME format. ------=_NextPart_000_0000_01D1AF70.59FC25F0 Content-Type: multipart/alternative; boundary="----=_NextPart_001_0001_01D1AF70.59FC25F0" ------=_NextPart_001_0001_01D1AF70.59FC25F0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Following is an embedded image: _____ test afterit ------=_NextPart_001_0001_01D1AF70.59FC25F0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: 7bit <!DOCTYPE html PUBLIC " -//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns = "http://www.w3.org/1999/xhtml" > <head ><meta http - equiv = "content-type" content = "text/html; charset=UTF-8" /></head ><body style = "font-family: Segoe UI; text-align:left;" ><i>Following is an embedded image:</i><br /><img alt = "" src ="<file:///file.png>"/><hr><b>test afterit</b></body ></html > ------=_NextPart_001_0001_01D1AF70.59FC25F0-- ------=_NextPart_000_0000_01D1AF70.59FC25F0 Content-Type: image/png; name="file.png" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="file.png" iVBORw0KGgoAAAANSUhEUgAAADQAAABLCAMAAAAI0l 课程时，您的原始电子邮件将如下所示：

Object.freeze()

正如您所看到的，没有添加Content-ID标头，并且.Net实现中没有添加该标头的代码路径。

答案 1 :(得分：0)

它可能无法在指定的路径中找到图像，或者它可能是一个权限事物，因此破坏的图像很重要。您需要先检查它，但如果您使用base64，则会将图像放在字符串中。

尝试将图片更改为base64 link to a free online converter page.

此链接也可能有用c# embed base64 image for emailing.

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