AlainMi The entire mail client is not Public API. There is a story in the backlog to provide an official public API, but the story is not groomed and does not seem to be planned for implementation shortly.
For LTS 10.0 there is a builder for creating an Attachment. Attachment.create()
. I guess the builder should be self-describing. Otherwise don't hesitate to ask.
P.S. Using non-public API's can change at anytime.