IMO it makes sense for sites to actively block emails from this kind of service where their intention is to build an email list.
Hmm, are the claims of blocking spam correct? In many cases the emails may be part of an auto-responder sequence that the user subscribed to. But having viewed the stats page that Aquarezz linked to above (showing 100 or so emails per day per inbox), it looks like it is indeed blocking spam. Maybe the users are subscribing to FFA link pages?
Whatever, the site design looks good.