split_spf: Split out all SPF records in a domain's TXT record
Description
Given a vector of TXT records, this function will return a list of vectors
of all the SPF records for each. If the given TXT record is not an SPF
record, NA is returned (which makes it easy to skip with purrr
functions).
Usage
split_spf(spf_rec)
Arguments
spf_rec
a character vector of DNS TXT records
Value
list; each element is chr vector of spf components