Re: [Exim] bydns_mx (again!) and mbx format questions

| We currently have:
|
| # If it ain't for me, send it to the mail HUB
| hub_route:
| driver = domainlist
| transport = remote_smtp
| route_list = "* ukc.ac.uk bydns_mx"
|
| on many mail machines. This works well with <v4 and allows us to add/remove/
| generally fiddle with the mx machines as and when we want to. As this config
| is on many machines (including some that we don't have direct control over)
| it would be nice to replicate this functionality with Exim 4.
|
| Just to complicate things we have currently (and this is likely to get no
| better in the short term) at least two groups of machines that really need
| to have priorities working.
|
| route_list = * mx1.kent.ac.uk:mx2.kent.ac.uk:+:mx3.kent.ac.uk
|
| Is a big help (cheers!) but still has hardcoded machine names/aliases
| and when we bring more MX machine into service it will need amending
| (annoying on our machines - difficult on machines that we do not manage).


A bit ugly, but is this any use:

route_list = * relay1:relay2:relay3:relay4

where relay[1-N] are forward-only A records or CNAMEs pointing at
whichever mailhubs are currently in service, in whichever order you
prefer. No harm in 2 or more pointing to the same box - exim just
generates a list of unique IPs. Only problem is if you ever want more
than (e.g. 4) coded into every config.

One advantage - these aliases need not always point to the same machines
that receive your incoming external mail. You might one day have
dedicated systems for this job. Then, when you get the _really big_ DDoS
collateral spam attack, your internal mail service should be unaffected...

--
Chris Edwards, Glasgow University Computing Service