Always perform DNS lookup limit validation

[fernandomm]

I started using this gem but I'm having some issues related to the DNS lookup limit.

The validation error will happen depending on the mechanism order. If I have the following DNS zone with an SPF record that results in 11 DNS lookups:

example.com. IN 	A       2.2.2.2
example.com. IN 	TXT     "v=spf1 a:s1.h.example.com a:s2.h.example.com a:s3.h.example.com a:s4.h.example.com a:s5.h.example.com a:s6.h.example.com a:s7.h.example.com a:s8.h.example.com a:s9.h.example.com a:s1.h0.example.com a ~all"
*.h.example.com. IN A       1.1.1.1

This will work, because the IP 1.1.1.1 is found in "a:s1.h.example.com":

Coppertone::SpfService.authenticate_email('1.1.1.1',
                                                   '[email protected]',
                                                   'example.com')

But this one will fail because the IP 2.2.2.2 is only found in "a" mechanism and, at this point, it exceeds the number of allowed DNS lookups:

Coppertone::SpfService.authenticate_email('2.2.2.2',
                                                   '[email protected]',
                                                   'example.com')

Is it possible to force the DNS lookup validation to always run?

I tested several SMTP servers/antispam systems and it looks like this is the most common behavior.

Thanks!