domain blocking for DNS

[Hanasaki JiJi]

Adding a parallel thread to "domain blocking due to spam".

Some of you might have noticed a msg sent to me via the list becuase the 
sender was being bounced when sent directly.  I recently added a 
configuration to my mailserver to reject connections from sources that 
do not have forward/reverse DNS setup.

This resulted in alot of rejections from ligitimate companies and 
induviduals!  It was put into place becuase some spam seems to come from 
telnet sessions on an IP that has no DNS / ReverseDNS entry.

Do you folks think it is reasonable to expect admins to have both DNS 
and ReverseDNS propperly configured?  at least for their outgoing 
mailserver?

Thanks