Dave Crocker wrote:
ned+ietf-smtp(_at_)mrochek(_dot_)com wrote:
And this is what I was getting at when I said that I'm concerned that the
labelling is insufficiently unique in format. Mind you, I'm not
proposing a change here, merely expressing concern.
Really. If someone wants the current syntax changed, please do propose
it, explaining why it is needed.
As an example, one might propose replacing "prvs" with "batv1", e.g.
batv1=1234abcdef=user(_at_)example(_dot_)com(_dot_) Not that I like it very much, as
people will tend to read it as "BAT version 1". However, it can be
identified with a reasonably tight regular expression. Further
mechanisms would be numbered by their position in that IANA registry.
A C written program can easily scan the tag even without resorting to
regular expressions. Why would it want to do that? Two reasons:
1) Given that today is 019, the tag exemplified above exhibits an
expired day 234, thus a remote server can reject the message if it
adopts the policy of not accepting unbounceable messages, even if it
cannot verify the signature. (Possibly valid for batv1 only.)
2) A receiving MTA can extract user(_at_)example(_dot_)com if it needs to check
it against a list of subscribed users at the MAIL FROM level. (Also
valid for future BATV mechanisms.)