availability of post or post_ID when using s2_html_email et al

When using the s2_html_email filter, only the post content is passed as a parameter. But often, some meta information about the post is needed – and is usually available via one of the methods:

• global $post
• get_the_ID()
• get_queried_object_id()

However, when a post transitions from scheduled to published, ie. via timer instead of manual – none of those methods seem to yield the post, or its ID.
Unless there is some other method of obtaining the post in that unique situation, it would be enormously useful if the post, or its ID, could be passed as a 2nd parameter to s2_html_email filter.