Chris G wrote:
Isn't there an issue with what exactly "example.com" means? There would surely be issues with domains such as bt.com which probably have tens of thousands (if not hundreds of thousands) of users and probably no 'single source' such that mail from them could be signed consistently.
That would be a problem with things as I was looking at it, but could probably be worked around. I'm going off to look at DKIM now (thank's, Brett).
Come to that even one of my domains, isbd.net, resides on two totally separate (and separately administered) machines.
That shouldn't matter, provided you (as admin of isbd.net) know the private key for your domain.