Displaying mails with embedded images e.g cid:filename.jpg

Question

I fetch mails via imap. The server returns some mails with embedded images with the src attributes as <img src="cid:filename.jpg">. When i render this mail as html, the images appears broken.

Please note: I have downloaded the Visuals and saved it to a folder. Could this be the reason? Did i lose the files after downloading the visuals?

Answer 1

In most cases HTML body of the message references attached images using special "cid:" protocol. It specifies the Content-ID of the image, not the name of the file:

This is our <strong>brand new</strong> logo: <br />
<img src="cid:logo@example.com" />

The actual image is embedded inside an email, as a part of a MIME tree, as an element related to the HTML body and with content-disposition header set to inline.

You should use IMail.SaveHtmlAs method. It saves HTML version of the message body as regular HTML file (changing cid: references). All visual elements are saved as files in the same folder.

If the message is plain text only, this method uses GetBodyAsHtml() to create HTML from plain text.

Comments

Actually, i want all mails as html including text as html. so i used string body = email.GetBodyAsHtml();

Mail.SaveHtmlAs saves it as a file in a folder. i dont want that. i want it as string with proper referencing to images sources whether locally or remotely hosted images without the cid: prefixing.

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cid protocol is the only proper image reference. Image is not stored on disk but inside the email message (inside a MIME tree).

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When you access the Mime tree of the email message and save the visuals in a folder, does it affect the MIME Tree thereby breaking the cid: references to the Visuals. In my code below, i accessed the mime tree and saved the Visuals in a folder. Could this be the reason why cid: references fails. I'm currently having the thought to delete the code that extracts visuals

foreach (MimeData mime in email.Visuals)
{
   string guidattach = Guid.NewGuid().ToString() + "☻" + mime.SafeFileName;
   string newfilename = attachmentfolder + guidattach;
   string virtualfilename =    "~\\other_attach\\externalmail_attachment\\" + guidattach;
   mime.Save(newfilename);
   pagesb.Append(virtualfilename + ">");
}

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Saving MimeData element doesn't affect the MIME tree in any way.

I think your problem is elsewhere:
If you save the HTML and visuals to a single folder, browser won't be able to use cid references. Files on disk don't have content-id assigned. Cid references are useless in such case. Cid have a meaning in terms of the MIME document.

You need to modify html to point to actual files on disk, and this is what IMail.SaveAsHtml method does.