We just finished dealing with some new regulatory requirements (Regulation Best Interest and Form CRS, if you're curious). Among other things, we now send an automated email (containing a link to Form CRS) when someone opens a new account.
This email contains an embedded (or inline) image using CID. I noticed that the embedded image was not displaying in Gmail, but it was displaying in the other email clients I tested just fine. The problem? I didn't specify the Content-ID header for the attachment.
The email is sent using an Azure Function (written in C#) which uses Microsoft Graph to connect to Office 365.
Image in Email:
<p>
<img src="cid:email-img.png">
</p>
Azure Function:
I'm using a Graph client instance to send an email with an attachment, the attachment being the image I want to appear inline. The key part here is that you specify the ContentId property in the FileAttachment object, which ends up as the Content-ID header. It should match the attachment name.
Before I added this, the inline image was not appearing in Gmail clients.
Attachments = new MessageAttachmentsCollectionPage()
{
new FileAttachment
{
Name = "email-img.png",
ContentType = "image/png",
ContentBytes = attachmentBytes,
ContentId = "email-img.png" // don't forget this part
}
}
It took me a little bit of time and research to figure this out as I'm still pretty "green" with Microsoft Graph, but maybe this post will save someone else a little time down the road!
