Scott Kitterman wrote:
I agree. It is reasonable. But it is also reasonable to expect big
providers to, if they are publishing, give accurate and exact SPF
records and describe their entire email sending infrastructure. This
may mean large, complex SPF records. People should do what they can to
work together and make it easier on each other (ISPs providing as
succinct records as possible, for example, or simplifying their network
layout), but in some cases this may not be possible if the services that
the ISP provides are wide ranging or complex or reliable, which may
require more complexity and length to describe.
Which is exactly why your 10 limit is way to low. If you said to per level
(i.e. 10 in my record and 10 in each record I include), then I'd be inclined
to see it as reasonable. You'd have to specify a maximum depth then...
But that adds up to 111 queries - is that reasonable ?
Because of the recursion, the total number of queries grows
exponentially. We need to specify an absolute cumulative number.
I think a per-record limit is very dangerous, since it has this
exponential pyramid problem.