outbound:
    driver =    dnslookup
    # if outbound, and forwarding has been done, use an alternate transport
    domains =   ! +local_domains
    transport = ${if eq {$local_part@$domain} \
                        {$original_local_part@$original_domain} \
                     {remote_smtp} {remote_forwarded_smtp}}

  inbound_srs:
    driver =    redirect
    senders =   :
    domains =   +local_domains
    # detect inbound bounces which are SRS'd, and decode them
    condition = ${if inbound_srs {$local_part} {SRS_SECRET}}
    data =      $srs_recipient

  inbound_srs_failure:
    driver =    redirect
    senders =   :
    domains =   +local_domains
    # detect inbound bounces which look SRS'd but are invalid
    condition = ${if inbound_srs {$local_part} {}}
    allow_fail
    data =      :fail: Invalid SRS recipient address