DNS Template for empty Domains.
# Prevents sender spoofing for domains which do not send emails
example.com IN TXT v=spf1 -all
_dmarc.example.com IN TXT p=reject
# Indicates that this domain cannot receive emails.
# https://tools.ietf.org/html/rfc7505
#
# Otherwise, some senders do a fallback to the A or AAAA-Record
# and try several times until delivery fails
example.com IN MX 0 .