Does anyone know how I get notifications in my training instance from unknown user?

[Gloria Landsberg]

Hi community, 

I have a question that I am not able to find an answer so far. 

In my instance that I use for my training purposes, but it's empty right now

I received strange notification for tickets that I have been mentioned. 

And in addition - I just discovered those instances that I don't recognize and never have been part of.  

Neither of them rings the bell to me. 

Has anyone got the same or similar issue? 

Any comments are more than welcomed, as I am getting a bit Am I too paranoid to where my user's account was added, so I am getting notifications. 

Or I shall ask support on this? 

Thank you,