double @ problem on mail forwarding

Hi, all

I'm using qmail-ldap with maildrop.  I set the mail forwarding by .mailfilter like this :

cat .mailfilter 
cc "! [email protected] " 

when I sent the mail from sohu.com to [email protected] . 
the [email protected] is forwaring the mail to [email protected] using .mailfilter file above
the log shows:

@400000004923daa83625b79c info msg 6619371: bytes 5410 from <[email protected]> qp 13683 uid 604
@400000004923daa83625bb84 starting delivery 14: msg 6619371 to local [email protected]
@400000004923daa83625c354 status: local 1/20 remote 0/20
@400000004923daa9041a83a4 new msg 6619573
@400000004923daa9041a8b74 info msg 6619573: bytes 5481 from <[email protected]@mail01.east.net> qp 13690 uid 620     ---double @
@400000004923daa9041a9344 starting delivery 15: msg 6619573 to remote [email protected]
@400000004923daa9041a972c status: local 1/20 remote 1/20
@400000004923daa904f7b0bc delivery 14: success: did_0+0+1/
@400000004923daa904f7b88c status: local 0/20 remote 1/20
@400000004923daa904f7bc74 end msg 6619371

some mail servers(etc hotmail.com) does't receive the forwarding mail because the "MAIL FROM:" is invalid reverse DNS(double @).

what can be the reasons? how can i fix it ? please help me

     Thanks & Regards,

RaidCheng