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postmarkapp.comemail setup

Public DNS report for postmarkapp.com, read on September 27, 2026: authentication, the email tools its records reveal, the sender rules it meets, and what would raise its score. Every line is a public record.

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The Email StackPublic DNS Report
Report
TES-20260927-1E2E3E
Read
27 Sept 2026, 12:53 UTC
Source
Index snapshot
Domain

postmarkapp.com

The three core checks pass. What is missing is the transport and trust layer around them.

4 of 8 checks pass · 4 tools visible in DNS · nothing urgent

C 75/100 Grade C
SPFValid, soft fail20/20
DKIM2 keys found15/15
DMARCEnforced (p=reject)30/30
MX5 hosts10/10
MTA-STSNot published0/10
TLS-RPTNot published0/5
BIMINot published0/5
DNSSECNot signed0/5

1 · Authentication and transport

SPF

PassValid, soft fail

Anything not on the list is accepted but marked. Google recommends ~all; with DMARC enforced it is as strong as -all.

v=spf1 a mx include:spf.mtasv.net include:_spf.google.com include:cmail1.com include:mail.zendesk.com include:helpscoutemail.com ~all

DKIM

Pass2 keys found

Selectors google, pm publish a public key.

google._domainkey, pm._domainkey

DMARC

PassEnforced (p=reject)

Failing mail is rejected. This is the finish line.

v=DMARC1; p=reject; pct=100; rua=mailto:re+j1puxgl6ln5@inbound.dmarcdigests.com; sp=none;

MX

Pass5 hosts

More than one receiving server, so a single outage does not bounce mail.

10 aspmx.l.google.com
20 alt1.aspmx.l.google.com
30 alt2.aspmx.l.google.com
40 aspmx2.googlemail.com
50 aspmx3.googlemail.com

MTA-STS

ReviewNot published

Sending servers cannot tell that this domain requires TLS, so inbound mail can be downgraded to plain text by anyone on the path.

TLS-RPT

OptionalNot published

Nobody is told when TLS to this domain fails. Cheap to add once MTA-STS is in place.

BIMI

OptionalNot published

DMARC is enforced, so this domain qualifies. Yahoo and Fastmail show the logo from the record alone; Gmail and Apple Mail also need a paid VMC or CMC certificate.

DNSSEC

OptionalNot signed

Optional. Signing the zone protects every record in this report from tampering.

2 · Tools visible in DNS

LayerToolEvidence
MailboxGoogle WorkspaceMX aspmx.l.google.com
TransactionalPostmarkSPF include:spf.mtasv.net
SupportHelp ScoutSPF include:helpscoutemail.com
SupportZendeskSPF include:mail.zendesk.com

Only tools that leave a DNS trace appear. A shared DKIM selector is attributed only when its CNAME target names the vendor.

3 · Sender requirements (Google, Yahoo, Microsoft)

RequirementApplies toStatusNote
Authenticate with SPF or DKIMGoogleYahooMicrosoftVerifiedAt least one method is in place.
Bulk senders: both SPF and DKIMGoogleYahooVerifiedBoth are present.
Publish a DMARC record (p=none is enough)GoogleYahooMicrosoftVerifiedPolicy is p=reject.
From: domain aligns with SPF or DKIMGoogleYahooMicrosoftNot checkable hereNeeds a real message. The Send-a-Test report will check this.
Valid forward and reverse DNS for sending IPsGoogleYahooNot checkable hereDepends on the sending server, not the domain.
Encrypt in transit (TLS)GoogleYahooNot checkable hereOutbound TLS depends on your sending tool; MTA-STS would cover inbound.
One-click unsubscribe (RFC 8058) for marketing mailGoogleYahooNot checkable hereA message header, not a DNS record. Microsoft recommends it rather than requiring it.
Spam complaint rate under 0.1% (0.3% is the hard limit)GoogleYahooNot checkable hereRead it in Google Postmaster Tools and Yahoo Sender Hub. Google’s target is 0.1%; 0.3% is where enforcement starts.

4 · What to fix, in order

  1. P3

    Publish MTA-STS (record and policy file)

    Tells sending servers to require TLS to your MX hosts, which prevents downgrade attacks. The TXT record alone does nothing: the policy file must be served over HTTPS at mta-sts.postmarkapp.com. Start in testing mode, watch TLS-RPT, then switch to enforce.

    Publish at_mta-sts.postmarkapp.com and https://mta-sts.postmarkapp.com/.well-known/mta-sts.txt
    TXT  v=STSv1; id=2026100401

mta-sts.txt:
version: STSv1
mode: testing
mx: aspmx.l.google.com
mx: alt1.aspmx.l.google.com
mx: alt2.aspmx.l.google.com
mx: aspmx2.googlemail.com
mx: aspmx3.googlemail.com
max_age: 86400
  2. P3

    Publish TLS-RPT

    You get a report when TLS delivery to your domain fails; this is what notices a downgrade that MTA-STS is meant to prevent. The address must exist.

    Publish at_smtp._tls.postmarkapp.com
    v=TLSRPTv1; rua=mailto:tls-rpt@postmarkapp.com
  3. P3

    Add a BIMI logo record (optional)

    DMARC already qualifies. The logo must be SVG Tiny PS, square, served over HTTPS. Yahoo and Fastmail show it from the record alone; Gmail and Apple Mail also need a paid VMC or CMC certificate, and a VMC needs a registered trademark. Skip this unless the certificate is worth it to you.

    Publish atdefault._bimi.postmarkapp.com
    v=BIMI1; l=https://postmarkapp.com/.well-known/bimi.svg;
  4. P3

    Sign the zone with DNSSEC

    Protects every record in this report from being swapped in transit. Two steps: enable signing at your DNS host (one switch at Cloudflare and most others), then add the DS record it gives you at your registrar.

    Publish atpostmarkapp.com

Appendix · Raw DNS answers

NameTypeAnswer
postmarkapp.comMX10 aspmx.l.google.com
20 alt1.aspmx.l.google.com
30 alt2.aspmx.l.google.com
40 aspmx2.googlemail.com
50 aspmx3.googlemail.com
postmarkapp.comA94.247.142.1
postmarkapp.comTXTv=spf1 a mx include:spf.mtasv.net include:_spf.google.com include:cmail1.com include:mail.zendesk.com include:helpscoutemail.com ~all
(+ 6 other TXT records: site-verification tokens and the like, omitted)
_dmarc.postmarkapp.comTXTv=DMARC1; p=reject; pct=100; rua=mailto:re+j1puxgl6ln5@inbound.dmarcdigests.com; sp=none;
<selector>._domainkey.postmarkapp.comTXTgoogle → key published
pm → key published
_mta-sts.postmarkapp.comTXT3kc6stb9z74qkxdg404zl20bgsbqp2fh
_smtp._tls.postmarkapp.comTXT3kc6stb9z74qkxdg404zl20bgsbqp2fh
default._bimi.postmarkapp.comTXT3kc6stb9z74qkxdg404zl20bgsbqp2fh

How to verify this yourself. Every line above comes from public DNS. Run dig TXT _dmarc.postmarkapp.com or dig MX postmarkapp.com and compare. Method: theemailstack.com/methodology.

Scores weigh SPF 20, DKIM 15, DMARC 30, MX 10, MTA-STS 10, TLS-RPT 5, BIMI 5, DNSSEC 5. Message-level requirements (alignment, unsubscribe headers, complaint rate) are not checkable from DNS and are marked as such, never guessed.

Scan to re-run livetheemailstack.com/report/postmarkapp.com

About this report

The Email Stack reads public DNS for well-known domains and publishes the result as a report, the same one anyone can generate for any domain at /report. It is a point-in-time read: records change, and a domain that scores C today may score differently next month. The "Re-run live" button reads DNS again in your browser.

Scores weigh SPF 20, DKIM 15, DMARC 30, MX 10, MTA-STS 10, TLS-RPT 5, BIMI 5 and DNSSEC 5. Tools are named only when a DNS record names the vendor; a shared DKIM selector counts only when its CNAME target does. Message-level requirements such as alignment and one-click unsubscribe cannot be read from DNS and are marked as such, never guessed. Method: how we detect tools.

Own this domain and see something wrong? DNS is the source; fix the record and the next read will show it. Questions to hello@theemailstack.com.