Thank you, suggestion.

Well, that function need to consideration to add.

Because sometime it works not fair use. There is no opt-in mechanism, now.
Also it will be complex function if enough implementation.
(remove duplicates, make to comment in message, opt-in mechanism, bulk email job handle, etc).

Of cause, limited implementation(just send email) will be easy. But it will be broken contacting model in this module (can not track follow-up information).