linux to an imac: 2003/03: ADSL bunnies::titchy little exim recipe

I'm now the puzzled owner of a promotional tea-towel heralding the delight brought to a family of rabbits after they sign up to BT's Home Network 1200.

e.g.: Susie was surprised that to find there were no websites dedicated to radishes, so she emailed 'fancysalads.com' to enquire about the lack of information. Daddy Rabbit caught up with the latest fox avoidance techniques and Mummy could chat as long as she wanted to Aunt Mimi. Oh what joy!

'Home Network 1200' is itself a clever bunny, in that it uses your standard telephone wires / extensions as the physical layer of a LAN (with technology from HomePNA). For £249 you seem to get an ADSL modem/firewall/NAT router/HomePNA router, and USB adaptors for two PCs. Additional PC adaptors come in at £50 a shot. Pricey.

The topologies can also get a bit fiddly.

2003-03-06 10:28 / titchy little exim recipe »

The problem with having an entire domain of mail sent to the same inbox is that some random toad can 'steal' a localpart and use it for registration on feckless websites. So you start getting spam after spam for an address you've never even used.

Exim is a delight here, with its limit on configuration seemingly being just your imagination and ability to think up 'recipes'. The router below looks for files called <your_domain>.reject, and bounces mail with a 550 'invalid recipient' to any localpart listed there. It could probably be better, but it works, and reduces our bandwidth consumption.

EXIM_ETC = /usr/local/etc/exim

bounce_addresses:
        driver = redirect
        domains = dsearch;EXIM_ETC/domains/
        local_parts = lsearch*;EXIM_ETC/domains/$domain.reject
        allow_fail
        data = :fail: Invalid recipient

MBM has some crazy-arsed exim filters, including how to process baited, time-limited, and one-use addresses.

It's easy enough to install and run on OS X too, as a replacement for the default sendmail that Apple install. You'll probably want to set up a StartupItems script, but without mailer.conf, there's dangerous installer-overwritten symlinks to muck about with too. (i.e. ln -s /usr/local/exim/bin/exim /usr/sbin/sendmail.)