On Tue, Jun 01, 2004 at 04:46:51PM -0400, Stuart D. Gathman wrote:
|
| There is actually no need for any mechanism other than exists. The other
| mechanisms exist only as an optimization for common checks which can be safely
| performed on the receiving MTA without consulting the sender domain.
The above is true if we limit sender authentication to
designated sender schemes. However, if we admit the
possibility of non-IP-based schemes eg. DomainKeys, PGP,
SMIME, Vanquish, PennyBlack, etc etc, the case for new
mechanisms makes more sense.