User to user email
Hi @evoixmr ,
Don't think it exists.
For users that have public email selected in user>settings page, you could send and e-mail just using your email client directly, so the plugin would not have any sense in my opinion; and for the users who have their e-mail hidden, in my opinion again, the plugin should respect the user's choice and don't let anyone see/use their e-mail adress, so you should not be able to contact them via e-mail even with the plugin approach you are suggesting.
That said you send a chat message to someone, they receive an email if they have selected the related option once again in user>settings page wich i even think can be selected as a default setting from the Administration Control Panel for all users to have by default.