I am not aware of a feature/option to send a PM to any user on the Biostar network. Wouldn't it be nice to include as it will eliminate the need to search for email id (hidden anyways) and the email user about something. Some users may want to talk about something which can be expressed as a comment/question and if it can, then might not be a interest of everyone.
I think having Inbox would be a cool addition, what you all say.
Thanks, I will write on GitHub asap. PM should also have a flag, private or public, if the user doesn't want the content to be shown in public in the form of feed else it would defeat the purpose of the PM. Also, I should definitely revise my scripting language skills now :)