transport nexthop nexthop

2 msg	Duplicate messages with always_bcc
14 msg	[OT] Saving outgoing email Gmail style
3 msg	451 error
10 msg	Postfix 2.5 release candidate (and 2.6 snapshot...
2 msg	postfix errors when sending smtp auth via yahoo
4 msg	Documentation enhancement: Adjusting DB file pe...
11 msg	I don't want Postfix to confirm users via telnet
3 msg	Question on Earthlink and dnsbl.sorbs.net
36 msg	Re: Enforced Outbound TLS (part deux)
6 msg	smtpd_proxy_filter to unix: problem
4 msg	Again troubles with postfix and cyrus-sasl
3 msg	Exclude local host from smtpd_proxy_filter

transport nexthop nexthop
\ Gary W. Smith (15 Jan 2008)
. \ (Wietse Venema) (15 Jan 2008)
. . \ Gary W. Smith (15 Jan 2008)
. \ Victor Duchovni (15 Jan 2008)

3 msg	TLS has been selected, but TLS support is not c...
2 msg	Which documentation to read for this..
4 msg	Exchange 2003 to Postfix maildir migration
7 msg	virtual_mailbox_base & LDAP
12 msg	Enforced Outbound TLS
2 msg	postfix+maildrop error
10 msg	Outgoing IP address

Subject:	transport nexthop nexthop
Group:	Postfix-users
From:	Gary W. Smith
Date:	15 Jan 2008

Hello,

We're using transport from a backup MX server to send email to the
primary MX via transport. Recently the primary location encountered a
significant outage that left it without reliable internet connection for
over a week (that it on the main lines -- 5 T1's all through different
providers all through one line carrier). Luckily we were able to get
one line back up and finally route some mail.

What we would like to do is keep the backup MX server using the
transport table and if that transport if offline to use a secondary IP
as a backup. In theory we could setup the slower line at the primary
location as a backup MX as well but we really don't want the excess
traffic unless we really need it, so basically it will be running an
unadvertised SMTP service.

Is there a simple way to do this in postfix. I looked at
fallback_transport and configured our test domain for this but when I
stopped traffic from the backup to the primary (via an iptables drop
rule for all traffic to mx1.domain.tld) it didn't fail over to the
fallback.

Here is what I have in main.cf
transport_maps = hash:/etc/postfix/transport
fallback_transport = hash:/etc/postfix/transport-fallback

/etc/postfix/transport
domain.tld smtp:[mx1.domain.tld]:25

/etc/postfix/transport
domain.tld smtp:[an_ip_address]:25

Any help would be greatly appreciated.

Gary Wayne Smith