Are you're business mail accnt an yahoo accnt?
If so I can see on you image that you are set as I am Available in the Chat and Mobile Text (to the lower left in the image)
Even though you're not using Yahoo messenger, you've set up your accnt so that others can see you and invite you. And it looks as some one has that believes they do know you.
I don't have an Yahoo accnt myself so I don't know the settings you can do. But you shouldn't be available.
Log into your accnt and change the settings.
If you get the invitation again decline it.
Did that solve it?