Extract URLs of attachments from attachments panes inside HTML body

Problem

GMail and Outlook clients provide convenient and interactive way to preview and manipulate attachments from the composer itself. User can hover on the attachment pane and remove/preview icons appears.

But these controls are leaking into MIME HTML at the sender side, and do not appear at the recipient. Hence, validation of these parts does not work.

In order to mitigate this inconsistency we must take into account only links to the attachments and ignore the rest styling and visual parts.

Accepance criteria

Take into account attachments URLs during the signing of the message, and ignore all the styling.

GMail

Outlook