Obscure problem: forwarded mail bouncing

[codesmith]

We have our domains set to reject mail if the user doesn't exist. However, one person has an email set up (example [email protected]) to forward to another email address (example [email protected]).

Say a spammer sends an email to [email protected] from [email protected].

Our server mydomain.com tries to forward the email but otherdomain.com has better spam controls and rejects the bad [email protected] email address. Our server mydomain.com now tries to bounce the email back to [email protected] which we don't want to happen. Any ideas on how we stop this bouncing?