checking addresses integrity

[player]

hey, my clients getting lots of spam from strange address that i cannot match with banned words, such as : lilypond-user-bounces+morelk=myorg.com@gnu.org return-6-581-levymic=myorg.com@drhinternet.net the funny thing is that they are passing through like a normal mail which they are not. is there engine that can verify the sender address? how can i match this kind of expressions??