Social　network　can　help　to　judge　the　trustworthiness　of　outsiders　and　was　widely　used　in　information　filtering.　Since　the　overall　topological　properties　were　hard　to　be　obtained,　the　use　of　social　network　based　methods　was　seriously　limited.　In　this　work,　emails＇　social　connections　were　reconstructed　based　on　reference　social　network　and　virtual　social　network,　and　two　new　approaches　of　spam　filtering,　reference　social　network　based　decision　(RSND)　and　virtual　social　network　based　decision　(VSND)　were　discussed.　These　approaches　can　be　used　as　complementary　tools　for　existing　anti-spam　systems　to　more　efficiently　block　organized　spammers.　The　experimental　results　in　real　emails　corpora　indicate　that　our　approaches　can　offer　the　better　chance　for　reliable　discrimination　between　spammers　and　legitimates.