Alan DeKok writes:
Has there been a demonstrated need for that extensibility?
MARID seems to be writing a sort of programming language. Mail senders
write a program, mail recipients provide an interpreter, run a program
provided by the claimed sender, and use the result to decide how to
handle the message.
Of course it needs to be extensible. When was there ever a scripting
language that didn't need extensibility.
But I question whether that language is a beneficial in the first place.
Consider this strawman, which attempts to get rid of the scripting
language:
1. A mail recipient looks up _friday._udp.senderdoma.in. (It's Friday today.)
2. If that results in one or more servers, the recipient picks one and
sends an UDP packet containing a Friday query to that server. The
Friday query contains the MAIL FROM address and SMTP client's IPv4/IPv6
address.
3. The Friday server consider the three facts it has (recipient IP
address, sender IP address, claimed sender email address) along with
its configuration and other data. It answers "good", "bad" or "uh,
dunno".
4. The mail recipient gets a small UDP packet back with the answer.
There. Advantages:
1. No mini-java script language that must be implemented in all mail receivers.
2. The sending domain can implement any policy it wants.
3. No DNS lag for policy changes.
4. No coordination required with different departments when the policy
changes. (See earlier thread about email outsourcing, too.)
5. The protocol's much simpler.
Disadvantages:
1. DNS caching doesn't help (much).
Arnt