Oleg, they are apparently filtering based on content.  We get no bounce from them at all, and they will not talk to us.  So all we can do is guess.
2big, I appreciate your concern, but before you go off the deep end.  If you wish to discuss those matters, then do so privately.  Nothing you mentioned is really a problem for us.  And if companies are building spam fillters based on PTR records, then they are in the wrong, not us.
Our name service is a bit screwy as AT&T insists on handling the reverse lookups and refuses to make us authoritative for the IP block.
The only problem is with MSN/Hotmail and Yahoo.  They do not bounce thier emails when they decide not to deliver them.  I have a real problem with that.  If a service wishes to filter/block an email from delivery, they should bounce back with an error code indicating such.  Giving us a satisfactory delivery code, but not delivering the email is just wrong.