Email Blogging and spam?

I just come to know about a new service which supports the blogging by email.you only needs to send a mail containing a blog post and then this service will create a blog for you.No doubt it makes life much simple but then it can be misused easily.consider a case when someone want to spam the site as there are no login required some one can easily sent tons of spam from different ips,emails and the result will be dangerous.
so i m not going to tell the name of that site but would like to hear your views.post in comments on how you think this cab be prevented.[yes adding a login is simple and effective idea]