Issue Summary

"Unable to embed resource" message for new attachments that are not an image

Steps to Reproduce

1. Add an attachment to a JSM issue (not an image file)
2. Click on "Reply to customer" and save it to trigger a customer notification

Expected Results

The customer notification contains the file link for download.

Actual Results

The customer notification contains the message:
Unable to embed resource: "filename.extension" of type "filetype"

Workaround

Change the attachment's view option to "Display inline" before saving the comment.