Nice idea, but there are hidden traps in the context of user tracking.
If user set up SOCKS proxy for account - should this HTTP request for dog’s web page be sent from local IP address by default route, or through proxy?
What if proxy and mail server are the same host?
What if user’s browser, in which that dog’s page was opened initially, was accessing internet via same/another proxy?
And how DNS leaks will be prevented?