dmarc poc

network	count
STRATO-RZG-KA	2

domain	count
iguana.example.com	1
tapir.example.com	1

Phase 1 — Discovery: who is sending mail from your domains? ⓘYou have published p=none and are collecting data. Nobody is being blocked yet.

Focus on message volume, not IP count — a source sending 50 000 messages is urgent; one sending 3 is noise.

Both-fail sources (DKIM fail AND SPF fail) are either spoofing attempts or services that were set up without telling you. Surface these first.

Expand a domain, then open "By source IP" to see the quadrant breakdown per prefix group.

Sender landscape

both pass SPF fail DKIM fail both fail

iguana.example.com 1

100%

STRATO-RZG-KA total 1

IP	PTR	Total	DMARC failures share
81.169.146.148	mi4-p00-ob.smtp.rzone.de	1

google.com total 1

No DMARC failures from this reporter.

source IP	header-from	count	disposition	DKIM	SPF	report begin
81.169.146.148	iguana.example.com	1	none	pass	fail	2026-05-21 02:00

tapir.example.com 1

100%

STRATO-RZG-KA total 1

IP	PTR	Total	DMARC failures share
81.169.146.148	mi4-p00-ob.smtp.rzone.de	1

Enterprise Outlook total 1

No DMARC failures from this reporter.

source IP	header-from	count	disposition	DKIM	SPF	report begin
81.169.146.148	tapir.example.com	1	none	pass	fail	2026-05-10 02:00

Phase 2 — Hardening: what would break if you tightened the policy? ⓘYou understand your sender landscape and want to move from p=none toward p=quarantine or p=reject. The risk is collateral damage to legitimate mail.

Policy readiness % = share of messages that would survive a reject policy today.

SPF-only sources need DKIM signing added in their sending platform.

DKIM-only sources need their SPF record aligned with your From: domain.

No DMARC alignment sources send all mail failing — configure or block.

Inconsistent sources have mixed results — investigate per-IP.

DMARC readiness

both pass SPF fail DKIM fail both fail

iguana.example.com 1 / 1

100%

STRATO-RZG-KA 1 / 1

IP	PTR	Fail / Total	DMARC failures share
81.169.146.148	mi4-p00-ob.smtp.rzone.de	1 / 1

DKIM-only — SPF not aligned

google.com total 1

No DMARC failures from this reporter.

source IP	header-from	count	disposition	DKIM	SPF	report begin
81.169.146.148	iguana.example.com	1	none	pass	fail	2026-05-21 02:00

tapir.example.com 1 / 1

100%

STRATO-RZG-KA 1 / 1

IP	PTR	Fail / Total	DMARC failures share
81.169.146.148	mi4-p00-ob.smtp.rzone.de	1 / 1

DKIM-only — SPF not aligned

Enterprise Outlook total 1

No DMARC failures from this reporter.

source IP	header-from	count	disposition	DKIM	SPF	report begin
81.169.146.148	tapir.example.com	1	none	pass	fail	2026-05-10 02:00

Phase 3 — Steady state: did something break? Is anyone spoofing you? ⓘYou have a tight policy in place (p=quarantine or p=reject). Watch for anomalies.

New sources — an IP appearing for the first time in the last 30 days that was not seen before. Could be a new legitimate sender nobody configured, or the start of a spoofing campaign.

Active failures — sources still failing DMARC under a strict policy in the last 30 days. Persistent failures with high volume are either spoofing or a misconfigured legitimate service that needs fixing.

If a major reporter (Google, Microsoft) stops appearing, your rua= address may be bouncing.

Alignment health — last 30 days

both pass SPF fail DKIM fail both fail

05-10

05-21

iguana.example.com 1 / 1

100%

05-10

05-21

STRATO-RZG-KA new 1 / 1

IP	PTR	Fail / Total	DMARC failures share
81.169.146.148	mi4-p00-ob.smtp.rzone.de	0 / 1

google.com total 1

No DMARC failures from this reporter.

source IP	header-from	count	disposition	DKIM	SPF	report begin
81.169.146.148	iguana.example.com	1	none	pass	fail	2026-05-21 02:00

tapir.example.com 1 / 1

100%

05-10

05-21

STRATO-RZG-KA new 1 / 1

IP	PTR	Fail / Total	DMARC failures share
81.169.146.148	mi4-p00-ob.smtp.rzone.de	0 / 1

Enterprise Outlook total 1

No DMARC failures from this reporter.

source IP	header-from	count	disposition	DKIM	SPF	report begin
81.169.146.148	tapir.example.com	1	none	pass	fail	2026-05-10 02:00

dmarc poc

Top 10 source IPs

Top 10 header-from domains