To redirect one without changing the recipient address:
/etc/postfix main.cf:
transport_maps = hash:/etc/postfix/transport
/etc/postfix/transport:
[EMAIL PROTECTED] smtp:mx.b.example.com
Many years ago I tried to unify virtual aliasing and transport
mapping into one table, but I gave up because it would be too hard
to use, and it would be too fragile for regular expressions.
Wietse
