receiving mail gateway
Message
MAIL FROM alerts@chronos.orbital
Visible from ceo@chronos.orbital
not checked · SPF skips this
Signing domain idle · DKIM later
Host 198.51.100.25
DNS · SPF TXT
Policy for chronos.orbital
v=spf1 ip4:198.51.100.0/24 -all
Host ↔ DNS
Host (connecting IP) 198.51.100.25
vs
DNS SPF allow ip4:198.51.100.0/24
Compare Host to the MAIL FROM domain policy
SPF
fail
SPF
pass
Host → DNS → Pass
A pass is not safe. A domain is not a person.
SPF authorizes the host for the MAIL FROM domain.
SPF does not check Visible from.
Visible from still not checked
Mnemonic: Host → DNS → Pass
Step 1 of 8