On Wednesday, February 05, 2014 20:30:49 George wrote:
> Hi Chris, thanks again for the info.
>
> It would be great to configure some sort of automatic smarthost failover.
Turns out I needed something similar for myself, and ended up figuring out how
to do this. You mentioned you were running Debian Wheezy. Debian's Exim4
setup already comes with a "hubbed_hosts" router which checks for a file,
/etc/exim4/hubbed_hosts -- if it exists and the destination domain is listed
in the file, then it uses the line listed as a manualroute -- and /several/
destination hosts can be listed, along with destination ports. Such as this:
domain.example.net: "dest-2.example.net::587 : mail-2.ref.example"
To understand this better, see 'man 5 exim4_hubbed_hosts', as well as chapter
20.3 through 20.7 in the Exim 4.80 specification. This same man page explains
the format of the passwd.client file used to do SMTP AUTH with a remote
server.
The hubbed_hosts router normally uses the remote_smtp transport which doesn't
check for SMTP AUTH login information, but switching this to the
remote_smtp_smarthost router then does. ;-)
begin routers
[...]
hubbed_hosts:
debug_print = "R: hubbed_hosts for $domain"
driver = manualroute
domains = "${if exists{CONFDIR/hubbed_hosts}\
{partial-lsearch;CONFDIR/hubbed_hosts}\
fail}"
same_domain_copy_routing = yes
route_data = ${lookup{$domain}partial-lsearch{CONFDIR/hubbed_hosts}}
## Chris: changed transport to remote_smtp_smarthost to use SMTP AUTH
transport = remote_smtp_smarthost
The important difference in this case is that the remote_smtp_smarthost
transport checks /etc/exim4/passwd.client for SMTP AUTH login information for
particular servers.
begin transports
[...]
remote_smtp_smarthost:
debug_print = "T: remote_smtp_smarthost for $local_part@$domain"
driver = smtp
hosts_try_auth = <; ${if exists{CONFDIR/passwd.client} \
{\
${lookup{$host}nwildlsearch{CONFDIR/passwd.client}{$host_address}}\
}\
{} \
}
[...]
So from the hubbed_hosts entries we had this:
domain.example.net: "dest-2.example.net::587 : mail-2.ref.example"
And now in the passwd.client file you can make entries for each of the
smarthosts:
### target.mail.server.example:login:password
dest-2.example.net:login1:password1
mail-2.ref.example:login2:password2
So between hubbed_hosts and passwd.client you should be able to do manual
routing of mail for particular destination domains (including "*" for all
domains) using multiple smarthosts such that if one is down another is used
automatically.
-- Chris
--
Chris Knadle
[email protected]
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