There is a Blocked Senders Issue in the new e-mail implementation.
You cannot independently add e-mail addresses or domains to the Blocked Senders List. You can only delete items from the Blocked Senders. I learned this today by accidently deleting a domain from Blocked Senders and could not figure out a way to add it back in.
It appears you can only block a whole e-mail address by adding it to Block Senders from the Inbox.
You can however implement filters that will encompass whole domains, but really isn't the same thing.
Agree, need to be able to add and delete both e-mail addresses and domains in Blocked Sender and need to significantly increase the number of entries to keep up with increasing amount of spam. Need to do it soon.