Cannot embed images in email with MailKit - html

Question

This questions has been posed and answered several places on SO, specifically here : Issue with Gmail - Embedded images using MailKit
and handles my exact query, yet the answer doesn't seem to work for my case.
I've tried to build a simple mailer that embeds images in an HTML email, yet in several clients, all images still end up as attachments.
I suspect the fault to be in the way I handle the image attachments (one .gif and several .png) to be:
// Add pictures to embedded resources and replace links to pictures in the message
foreach (string imgpath in ImgPaths)
{
var image = builder.LinkedResources.Add(imgpath);
image.ContentId = MimeUtils.GenerateMessageId();
image.ContentDisposition = new ContentDisposition() { Disposition = ContentDisposition.Inline };
HtmlFormat = HtmlFormat.Replace(Path.GetFileName(imgpath), string.Format("cid:{0}", image.ContentId));
}
builder.HtmlBody = HtmlFormat;
message.Body = builder.ToMessageBody();
I can see from the emails (received in Gmail, for instance), do show that the images are being listed as:
src="images/cid:TPSXHQUDSAU4.JJRKUIEGLTZ5#Loralei"
All images are attached as attachments in both clients I've tried (gmail and roundcube). I've walked through your tutorials and checked out everything here: https://stackoverflow.com/search?q=Mailkit+Embed
Sadly, I just can't seem to find my error. Hopefully #jstedfast could see where I make my mistake?
UPDATE
As mentioned by #jstedfast, the corrected code should be (for my case anyway):
foreach (string imgpath in ImgPaths)
{
var test = Path.GetFileName(imgpath);
var image = builder.LinkedResources.Add(imgpath);
image.ContentId = MimeUtils.GenerateMessageId();
image.ContentDisposition = new ContentDisposition() { Disposition = ContentDisposition.Inline };
//HtmlFormat = HtmlFormat.Replace(Path.GetFileName(imgpath), string.Format("cid:{0}", image.ContentId));
HtmlFormat = HtmlFormat.Replace($"images/{test}", string.Format("cid:{0}", image.ContentId)); //use images/filename
}
This is a great guide to follow too, https://programming.vip/docs/5dac3983f0cd5.html

Answer 1

This looks like the problem:
<img src="images/cid:TPSXHQUDSAU4.JJRKUIEGLTZ5#Loralei" .../>
That needs to be:
<img src="cid:TPSXHQUDSAU4.JJRKUIEGLTZ5#Loralei" .../>
My guess is that in order to fix this, you'd change the following line of code:
HtmlFormat = HtmlFormat.Replace(Path.GetFileName(imgpath), string.Format("cid:{0}", image.ContentId));
to this:
HtmlFormat = HtmlFormat.Replace(imgpath, string.Format("cid:{0}", image.ContentId));
Hope that helps!