EDIT: Badly done Antispam is even more dengues... If your Antispam filter would reject all mails that had more then 10 recipients you would not be happy about it... If sender would not get a message that that happen it would be even a bigger problem in case it is a legit impotent mail... So just say if it has more then 200 outputs it is spam is really stupid way to do that...
Senders have to deal with that. This is a P2P network where you must assume the nodes you are talking to are hostile. I can even pretend to accept the transaction, and forget about it without relaying it. You have no way to know until you receive your transaction from other nodes, and even then it may be my nodes cooperating to fool you. So you better keep sending it to new nodes until you reach someone willing to mine it.