I run my own mail server and would like to use different addresses on the same domain. If I were to sign mails from those addresses, I'd have to generate new PGP keys for each and every one of them. This could become unmanageable very quickly.
As I understand it, DKIM signatures prevent the mail from being tampered with by other parties. Would it be possible / make sense to leverage DKIM for mail signing and just encrypt mail, skipping PGP signing? If it's possible, what assumptions would one have to make to reach comparable security? Would a DNSSEC secured domain be enough?