With rOd87848059727587be1f660283e0aeb3be16cc382 GpgOL ignores all content-ids for attachments. This differs a bit from Outlook which somehow detects if an image is referenced inline or not and hides the attachment because of that.
The reason for this is that as soon as we add a content-id tag to an image it will be hidden by outlook in the list of the attachments. This causes a felt data loss when we hide attachments which are not referenced in the HTML Mail. So they are not shown in the attachment list and not visible inline. Because some MUAs or Mail services always added a content-id to all attachments.
But of course it is now only possible to have GpgOL handle embedded images if their content-disposition is inline and not attachment.
We need to somewhat parse the html, at least very simplistic to detect if a content-id is referenced in the HTML body and then set it for outlook.