Email: Your requests are being blocked.

I am repeatedly getting what looks like a legitimate email saying my Azure requests are being blocked. 

However, when I log in, with the email address it is sent to, it says I can't access that page.  I have no idea which subscription this email refers to.  

If I click the link to find my list of organisations, none of them appear to relate to the email.

I presume it relates to a client that I no longer have access to, but how do I found out which one?