How to send embedded images with sendgrid emails?

问题

I'm starting with SendGrid to send my e-mails, but I coudn't find how to embed images. Without using SendGrid I was using the following code to send e-mails with embedded images:

var mail = new System.Net.Mail.MailMessage();
mail.Subject = "Warning";
mail.From = "from_user@test.com";
mail.To.Add("to_user@test.com");
mail.IsBodyHtml = true;
mail.Body = "<html><body><a href='http://www.mywebsite.com' title='My Website'><img src='cid:my_image' alt='My Image' border='0' /></a><br /><h1>My E-mail Title</h1>E-mail content.</body></html>";
var av = AlternateView.CreateAlternateViewFromString(mail.Body, null, "text/html");
av.LinkedResources.Add(new LinkedResource(@"C:\my_image.png", "image/png"){ContentId="my_image"});
mail.AlternateViews.Add(av);
var smtp = new SmtpClient("smtp.test.com");
smtp.Credentials = new NetworkCredential("user", "pass");
smtp.Send(mail);

--- EDITED ---

Now I'm using the following code to send my e-mails (using SendGrid classes).

var message = SendGrid.GetInstance();
message.Subject = "Warning";
message.From = new MailAddress("from_user@test.com");
message.To = new MailAddress[] { new MailAddress("to_user@test.com") };
message.Html = "<html><body><a href='http://www.mywebsite.com' title='My Website'><img src='cid:my_image' alt='My Image' border='0' /></a><br /><h1>My E-mail Title</h1>E-mail content.</body></html>";
var transportSMTP = SMTP.GetInstance(new NetworkCredential("user", "pass"));
transportSMTP.Deliver(message);

What I need to know is how to embed and link my images inside the e-mail using its content id (CID).

回答1:

I juggled around this for a little bit too. The solution was to Attach the image first and then to Embed afterwards with the direct name of the file in the email.

var myMessage = new SendGridMessage();
myMessage.AddTo("to@email.com");
myMessage.From = "from@email.com";
myMessage.Subject ="Forgotten Password";
string body = @"<div><img src='cid:email_reset' alt='Email Reset Header' border='0' /></div>" +
              @"<p>Content...</p>";

string att = Request.PhysicalApplicationPath + @"Content\files\images\email_reset.jpg";
var attachment = new Attachment(att, new ContentType("image/jpeg"));
var linkedResource = new LinkedResource(att, new ContentType("image/jpeg"));
myMessage.AddAttachment(attachment.ContentStream, attachment.Name);
myMessage.EmbedImage(attachment.Name, "email_reset");

myMessage.Text = WebUtility.HtmlDecode(Regex.Replace(body, "<[^>]*(>|$)", string.Empty));
myMessage.Html = body;

// Authenticate and Send the email

回答2:

I talked with a SendGrid customer support engineer and he directed me here..

https://github.com/sendgrid/sendgrid-csharp/blob/ca91fad22dfec2cd1219267fe979c1d9a33a522e/SendGrid/SendGridMail/SendGrid.cs#L211

So your code would be...

var message = SendGrid.GetInstance();
message.Subject = "Warning";
message.From = new MailAddress("from_user@test.com");
message.To = new MailAddress[] { new MailAddress("to_user@test.com") };
message.Html = "<html><body><a href='http://www.mywebsite.com' title='My Website'><img src='cid:my_image' alt='My Image' border='0' /></a><br /><h1>My E-mail Title</h1>E-mail content.</body></html>";

// added    
message.EmbedImage(@"C:\my_image.png","my_image");
// added

var transportSMTP = SMTP.GetInstance(new NetworkCredential("user", "pass"));
transportSMTP.Deliver(message);

I'm looking for a way to add a MemoryStream object instead of a filename, which it doesn't look like this is available yet.

回答3:

For anyone who is struggling with sending embedded images in the emails via SendGrid and using the stored templates, here's how it works:

/* In my case the images reside in the SQL DB as BLOBs but for this example it does not matter.
All you need is an array of bytes with your image.
*/
var imageContent = File.ReadAllBytes("Images\\logo_eml.jpg");
using (MemoryStream s = new MemoryStream(imageContent))
{
    ContentType ctype = new ContentType("image/jpg");
    var attachment = new System.Net.Mail.Attachment(s, ctype);
    var linkedResource = new LinkedResource(s, ctype);
    attachment.Name = "cibc_ins_logo_eml.jpg";
    emailMsg.AddAttachment(attachment.ContentStream, attachment.Name);
    emailMsg.EmbedImage(attachment.Name, linkedResource.ContentId + ".jpg");

    values.Add("%embedLogo%", linkedResource.ContentId + ".jpg");
}

string templateJSON = "{\"to\": [\"%to%\"],\r \"sub\": {\":name\": [\"%name%\"],\":embedLogo\": [\"%embedLogo%\"]},\r \"category\": [\"Quotes\"],\r \"filters\": {\"templates\": {\"settings\": {\"enable\": 1,\"template_id\": \"%templateid%\"}}}}"
emailMsg.Headers.Add("x-smtpapi", SubstituteTemplate(templateJSON, values));

The last line will replace the values. In my case it simply does a regex replace. This code will have to take care of substituting %embedLogo% in your particular JSON with the value of linkedResource.ContentId+".jpg" stored previously in the values which is a Dictionary<string,string>.

Here's what you need in the stored HTML template:

<img width="227" height="86" src="cid::embedLogo">

CID and two colons are critical.

Then Gmail will show the images embedded and not just attached!

来源：https://stackoverflow.com/questions/15753264/how-to-send-embedded-images-with-sendgrid-emails

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