Cristian Cadar writes:
Do you know any implementation where SMTP option is used by somebody
for delegating IPv4 SMTP server addresses to the clients?
I can't think of any right now. There may be some.
do you think that the SMTP option for DHCPv6 will be used in the
future by the email clients?
Unlikely. It (and the IPv4 option) is incompatible with SPF, and my bet
is that SPF will prove stronger. (Oversimplifying, SPF is a hacky way
to say "only these IP addresses may send mail from this domain".)
To see why it's incompatible, suppose you take your laptop along to the
IETF in Paris in two months, and that your company uses SPF at that
time. At the IETF, the DHCP server will give you an IP address. Perhaps
it also gives you an SMTP server. If your laptop that server, then
anyone who checks SPF will see that the IETF conference's SMTP server
is not allowed to send mail on behalf of netlab.nec.de.
Personally, I think the problem is more with SPF than with your draft.
However, in terms of realpolitik, SPF is IMO likely to be stronger.