I wonder how well the non-repudiation would actually hold up in that scenario. If you self host your mail server, the attacker could possibly steal your private key and forge the emails. So you might actually have repudiation. Or does DKIM have a timestamp? If not the attacker can simply send an email from your laptop and get it signed by your mailserver. Thus another route for claiming repudiation.
I'm not sure how common it is, but my mail server in particular doesn't store the signed emails, and I went to no special effort to set things up that way.
Of course, if someone replies to me and quotes my email to them, that will be signed by their server's key.
My reply was more to what tptacek said - observing that for at least some configurations a stolen mail spool from a laptop won't have signatures on sent emails.
I wonder how well the non-repudiation would actually hold up in that scenario. If you self host your mail server, the attacker could possibly steal your private key and forge the emails. So you might actually have repudiation. Or does DKIM have a timestamp? If not the attacker can simply send an email from your laptop and get it signed by your mailserver. Thus another route for claiming repudiation.