[plug] mailing lists and DKIM

[Adrian Woodley]

G'day PLUG,

I run a small not-for-profit ISP (bfb.asn.au) for my volunteer fire 
brigade, which offers Internet services (namely DNS, email and web 
hosting) for other volunteer fire brigades. One of the popular services 
is mailing lists, which use mailman.

Recently gmail started bouncing mail from the server, which has prompted 
me to implement DKIM. This works really well for mail originating from 
bfb.asn.au and it's sub-domains, but I'm a little unsure about how I 
should handing the mailing list.

As far as I can tell, there are two options:

1) prevent mailman from modifying any of the DKIM signed headers. This 
would include the From, Reply-to and Subject headers, which would 
prevent the mailing list from easily identifying itself (rather than 
email being from the original sender).

2) remove all DKIM signing, re-write the From header to be from the 
mailing list and re-sign the email upon transmission. This would make it 
potentially more difficult to identify who sent the email originally.

Any thoughts on what the best practise is here?

Cheers,

Adrian