(2) examples, one for IPv4 and the other for IPv6.
The IPv6 PTR lookup procedure took me ages to find an answer to...
We'll use Google's IP for the IPv4 example:
host -t PTR 22.214.171.124
This will break the SPF's check as a error will occur.
To be specific, that error will come; SPF PermError: too many DNS lookups
The mailflox will be affected as almost all servers/antispam check the ...