Aon Schweiz

aon.com

Industry: Consulting & audit
Headquarters: Zürich, Zurich
Type: listed
Checked on: 19 October 2026

75/100Grade B

Protection against forged senders: protected

Points per criterion

MX 10 / 10
SPF 15 / 15
DKIM 20 / 20
DMARC 25 / 25
DNSSEC 0 / 10
Transport (MTA-STS/DANE) 0 / 15
TLS-RPT 5 / 5

Industry avg.: 66.8 ▲ 8.2
Canton avg.: 53 ▲ 22
Overall avg.: 53.5 ▲ 21.5
Rank 13 of 45 in the industry

Findings

!DKIM key below 2048 bits

RSA-1024 is considered too weak (RFC 8301, M3AAWG). Rotate to 2048-bit keys.
!DNSSEC not enabled

Without DNSSEC, DNS answers can be forged in transit. DANE requires DNSSEC.
!No MTA-STS

Without MTA-STS (or DANE) inbound encryption is not enforced; an attacker on the path can downgrade to plain text.
iBIMI with mark certificate (VMC/CMC)

Logo with a verified mark certificate, shown by Gmail and Apple Mail among others. Requires DMARC enforcement.

Check live in the Mail DNS Check →

Who runs the mail?

Mailbox provider: Microsoft 365
Provider jurisdiction: USA · MX: US
Detection confidence: 100 / 100
Microsoft tenant: Federated · Aon
Tenant region: NA
Federated via: iam.aon.com

Signals (7)

MX	Microsoft 365	`aon-com.mail.protection.outlook.com`
SPF	Microsoft 365	`include:spf.protection.outlook.com`
DKIM	Microsoft 365	`selector1 → selector1-aon-com._domainkey.aon.onmicrosoft.com`
Network	Microsoft 365	`AS8075 MICROSOFT-CORP-MSN-AS-BLOCK - Microsoft Corporation`
Domain verification	Google Workspace	`google-site-verification=B1xVyEjI7Oy-M-0`
Domain verification	Amazon	`amazonses:YMAOVs9ptRA+eRfNkdSA65eT2xV34w`
Entra ID	Microsoft 365	`Entra-ID-Tenant (Federated)`

MX servers

Pref	Host	IP	Network	Country	TLSA
10	`aon-com.mail.protection.outlook.com`	`52.101.9.93`	AS8075 MICROSOFT-CORP-MSN-AS-BLOCK - Microsoft Corporation	US	–
		`52.101.194.17`	AS8075 MICROSOFT-CORP-MSN-AS-BLOCK - Microsoft Corporation	US
		`52.101.60.151`	AS8075 MICROSOFT-CORP-MSN-AS-BLOCK - Microsoft Corporation	US

SPF

v=spf1 include:spf.aon.net include:%{i}._ip.%{h}._ehlo.%{d}._spf.vali.email -all

all: -all
DNS lookups: 3 / 10
Includes: spf.aon.net
Detected sending services: Microsoft 365

DMARC

v=DMARC1; p=reject; fo=1; rua=mailto:dmarc_agg@vali.email; ruf=mailto:Mjk4MDcz@ruf.vali.email

Policy: p=reject
Subdomains (sp): inherits p=reject
Share (pct): 100 %
Alignment DKIM/SPF: relaxed / relaxed
Aggregate reports (rua): dmarc_agg@vali.email
Forensic reports (ruf): Mjk4MDcz@ruf.vali.email

DKIM

Selector	Key	delegated to
`dkim`	RSA 2048	–
`m1`	RSA 2048	–
`mailjet`	RSA 2048	–
`mandrill`	RSA 1024	–
`mta`	revoked	–
`s1`	RSA 2048	`s1.domainkey.u20308245.wl246.sendgrid.net`
`s2`	RSA 2048	`s2.domainkey.u20308245.wl246.sendgrid.net`
`selector1`	RSA 2048	`selector1-aon-com._domainkey.aon.onmicrosoft.com`
`selector2`	RSA 2048	`selector2-aon-com._domainkey.aon.onmicrosoft.com`
`smtp`	RSA 2048	–
`smtpapi`	RSA 1024	–

Checked: 100 common selectors. Keys under custom selectors remain invisible.

Transport encryption

MTA-STS: missing
DANE: missing
DNSSEC: missing
TLS-RPT: mailto:tls-report@vali.email
BIMI: VMC/CMC ✓ · Logo

Verified services

From verification records in the domain TXT: services where the domain is verified.

GoogleAppleMeta/FacebookAtlassianDocuSignCisco WebexAmazon SESOneTrustStripeGitHubFigmaZapierSmartsheet

History

19 October 2026 Score 75 · DMARC reject

All changes of this organisation in the change log →

Raw data

aon.com. IN MX 10 aon-com.mail.protection.outlook.com.
aon.com. IN TXT "v=spf1 include:spf.aon.net include:%{i}._ip.%{h}._ehlo.%{d}._spf.vali.email -all"
_dmarc.aon.com. IN TXT "v=DMARC1; p=reject; fo=1; rua=mailto:dmarc_agg@vali.email; ruf=mailto:Mjk4MDcz@ruf.vali.email"
_smtp._tls.aon.com. IN TXT "v=TLSRPTv1; rua=mailto:tls-report@vali.email"
default._bimi.aon.com. IN TXT "v=BIMI1; l=https://vmc.digicert.com/b8896f1b-258f-494d-8b95-684bd31c8bd9.svg; a=…"

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