aliasesでエイリアスを作っても適用されない(正確にはされていた)
問題解決。
logで
user@/etc/mailname.local
みたいになってた
/etc/mailname is set in the myorigin.
so i changed it.
myorigin = $mydomain
the problem is resolved!!
the mail sent from local seems to come from myorigin.
myorigin set /etc/mailname .
so postfix can't find mail.