eMail Subscriptions

hey internet!
really hoping someone might be able to help out with this:
the company i work for has a website-blog that is often updated –

http://www.sandboxstudio.com/blog

however, an old, outdated, no-longer-owned-by-us URL just became active & our email subscribers are receiving notifications –

http://sandboxstudioblog.com

any idea how to remove this URL (sandboxstudioblog.com) from our settings to make sure our subscribers no longer receive email alerts about a foreign blog?

thanks!

https://wordpress.org/plugins/subscribe2/