[Exim] Problems with sender callout.

Hello.

I'm using sender/callout option in my exim conf, and there's an valid
sender being blocked.

I read the specs and see that the callout is done trying to send a
bounce message to the sender host (using the mail from:<> syntax)

I tried to do the same thing, and discovered that when I try to send a
mail from <> to this domain i get an error, like:

Connected to mail.fujifilm.com.br.
Escape character is '^]'.
220 imss OK+SMTP 2002 Thu, 30 Jan 2003 12:05:35 -0300
helo x
250 imss Hello [200.194.1zz.zzz]
mail from:<>
501 <> : domain string is NULL.

And then the verify fails...

There's any ACL option to skip sender verify just for some buggy domains
or any other solution to deal with domains that doesn't take bounce
messages (!!) ?

thanks
core