Why not allow bounces? They are required by RFC822!
Originally, SpamCop made attempts to forgive misdirected bounce messages – to reject them as evidence of spam. However, there are two factors conspiring to force us to rescind this policy. First of course, is that these misdirected messages *are* spam as we define it (Unsolicited Bulk Mail). They are objectionable to recipients and can even cause denial of service to innocent third parties. Users of our blocking service want us to stop them. Second is that spammers have taken advantage of this policy, disguising their spam as bounce messages in order to avoid SpamCop. If we did not change the policy, this would become a highly popular way to “beat SpamCop”. Although bounces are required, it is possible to avoid the situation under which they are required (see above). So they aren’t really required unless you have already ‘painted yourself into a corner.
