Grant Thornton Schweiz/Liechtenstein

ch.gt.com

Industry: Consulting & audit
Headquarters: Zürich, Zurich
Type: private
Employees (approx.): 300
Checked on: 19 October 2026

68/100Grade B

Protection against forged senders: protected

Points per criterion

MX 10 / 10
SPF 13 / 15
DKIM 20 / 20
DMARC 25 / 25
DNSSEC 0 / 10
Transport (MTA-STS/DANE) 0 / 15
TLS-RPT 0 / 5

Industry avg.: 66.8 ▲ 1.2
Canton avg.: 53 ▲ 15
Overall avg.: 53.5 ▲ 14.5
Rank 26 of 45 in the industry

Findings

!External report receiver not authorised

The authorisation record for an external rua domain is missing (RFC 7489 §7.1); many receivers then send no reports.
!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.
!No TLS reporting (TLS-RPT)

Without TLS-RPT the organisation does not learn when senders fail to deliver encrypted.
iStrict DMARC alignment

adkim=s or aspf=s requires exact domain matches. Secure, but demanding when sending from subdomains.

Check live in the Mail DNS Check →

Who runs the mail?

Mailbox provider: Self-hosted / other
Upstream gateway: Mimecast
Provider jurisdiction: unclear · MX: GB
Detection confidence: 85 / 100
Microsoft tenant: Managed · Grant Thornton AG
Tenant region: EU

Signals (2)

Domain verification	Microsoft 365	`MS=ms24116990`
Entra ID	Microsoft 365	`Entra-ID-Tenant (Managed)`

MX servers

Pref	Host	IP	Network	Country	TLSA
10	`eu-smtp-inbound-1.mimecast.com`	`91.220.42.211`	AS42427 MIMECAST-UK - Mimecast Services Limited	GB	–
		`195.130.217.241`	AS42427 MIMECAST-UK - Mimecast Services Limited	GB
		`91.220.42.201`	AS42427 MIMECAST-UK - Mimecast Services Limited	GB
10	`eu-smtp-inbound-2.mimecast.com`	`91.220.42.211`	AS42427 MIMECAST-UK - Mimecast Services Limited	GB	–
		`91.220.42.241`	AS42427 MIMECAST-UK - Mimecast Services Limited	GB
		`91.220.42.201`	AS42427 MIMECAST-UK - Mimecast Services Limited	GB

SPF

v=spf1 include:_u.ch.gt.com._spf.dmarclyeu.com ~all

all: ~all
DNS lookups: 5 / 10
Includes: _u.ch.gt.com._spf.dmarclyeu.com

DMARC

v=DMARC1; p=reject; rua=mailto:dmarc_ag@mtf.ch; ruf=mailto:dmarc_fo@mtf.ch; sp=reject; adkim=s; aspf=s; pct=100; fo=0:1;

Policy: p=reject
Subdomains (sp): reject
Share (pct): 100 %
Alignment DKIM/SPF: strict / strict
Aggregate reports (rua): dmarc_ag@mtf.ch
Forensic reports (ruf): dmarc_fo@mtf.ch

DKIM

Selector	Key	delegated to
`mx`	RSA 1024	–

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

Transport encryption

MTA-STS: missing
DANE: missing
DNSSEC: missing
TLS-RPT: missing
BIMI: missing

Verified services

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

Microsoft 365

History

18 October 2026 Score 68 · DMARC reject

All changes of this organisation in the change log →

Raw data

ch.gt.com. IN MX 10 eu-smtp-inbound-1.mimecast.com.
ch.gt.com. IN MX 10 eu-smtp-inbound-2.mimecast.com.
ch.gt.com. IN TXT "v=spf1 include:_u.ch.gt.com._spf.dmarclyeu.com ~all"
_dmarc.ch.gt.com. IN TXT "v=DMARC1; p=reject; rua=mailto:dmarc_ag@mtf.ch; ruf=mailto:dmarc_fo@mtf.ch; sp=reject; adkim=s; aspf=s; pct=100; fo=0:1;"

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