Article - Private message

Hello, 
I need to create a link from a Joomla article (or from a custom HTML module displayed inside the article) that will open a private message directly to the user who wrote the article. What are the possible options to achieve this? 

Thank you for your help.

Probably doable using CB Auto Actions on Joomla content events. Where do you need this displayed exactly as locations will be limited. The easiest approach is to just override the article layout in your Joomla template and add the link there though as that lets you put it wherever you like.

Hello,
thank you for your reply. In my case it will be an override of a custom HTML module which is displayed inside the article. 
Could you please let me know how the link should look like in the code, so that it opens a private message directly to the article author?

Thank you.

I don't think you'll be able to do that. The module has no idea it's inside of an article. You'd have to use CB Content Bot to add a substitution directly in the article after setting its "User" parameter to "Author", your own insertion of the link using CB Auto Actions, or a article layout override.