Unless you have no more space available in your inbox, there is no way that one e-mail could keep you from receiving other e-mails.
If you are out of space, then, it's time to do some cleanup and suppress obsolete messages.
You can set a filter to automaticaly delete messages comming from a specific sender or with a given subject or key word in the title.
If the problem e-mails are legitimate, NEVER EVER mark them as spam. You'll hurt a legitimate business and all it's other subscribers.
Maybe the unsubscribe mechanism fail to work. Try again.
Electro, April 2015
