nginx.com

nginx.com · Last checked 2026-10-04 02:03 UTC

nginx.com

Excellent, with 1 thing to fix

nginx.com scored 92/100 (grade A). The main issue is DKIM key shorter than 2048 bits. Detected senders: Microsoft 365.

Checked 2026-10-04 02:03 UTC · fresh check

3 passed1 needs attention0 failing4 for informationDetected senders: Microsoft 365

All checks

MXCan servers find your inbox?No issues foundPass

Nothing to report.

SPFWho may send as you?SPF ends in softfail (~all)Info
  • Info: SPF ends in softfail (~all)

    "~all" is common and works well with DMARC. "-all" is stricter; switch when you are sure every sender is listed.

DKIMAre your emails signed?DKIM key shorter than 2048 bitsNeeds attention
  • Warning: DKIM key shorter than 2048 bits

    selector1 (1024-bit), selector2 (1024-bit) uses an RSA key below 2048 bits. Short keys can be factored and some receivers treat them as weak. Rotate to a 2048-bit key at your sending provider.

  • Pass: DKIM key published

    nginx.com publishes a DKIM key under selector1, selector2.

DMARCWhat happens to fakes?No issues foundPass

Nothing to report.

AlignmentDoes it match your From?No issues foundPass

Nothing to report.

BIMICan inboxes show your logo?No BIMI recordInfo
  • Info: No BIMI record

    No BIMI record at default._bimi.nginx.com. BIMI is optional: it shows your logo next to your mail in supporting inboxes once DMARC is enforced.

    How to fix this
MTA-STSIs mail to you encrypted?No MTA-STS recordInfo
  • Info: No MTA-STS record

    No MTA-STS record at _mta-sts.nginx.com. MTA-STS (RFC 8461) makes sending servers require TLS and a valid certificate when delivering to you, which blocks downgrade attacks.

    How to fix this
TLS-RPTWill you hear about failures?No TLS-RPT recordInfo
  • Info: No TLS-RPT record

    No TLS reporting record at _smtp._tls.nginx.com. TLS-RPT (RFC 8460) tells senders where to send daily reports about failed encrypted deliveries to you.

    How to fix this

How to fix it

Publish the MTA-STS recordTXT

Tells sending servers that nginx.com publishes an MTA-STS policy at https://mta-sts.nginx.com/.well-known/mta-sts.txt. Change the id whenever the policy file changes.

TypeTXT
Name / Host
_mta-sts.nginx.com

Some DNS providers want just “_mta-sts” here.

Value
v=STSv1; id=202610040203

Host the MTA-STS policy filepolicy-file

Serve this file over HTTPS with a valid certificate for mta-sts.nginx.com. It lists your MX hosts and starts in testing mode; switch to mode: enforce once TLS-RPT reports show no failures.

Location
https://mta-sts.nginx.com/.well-known/mta-sts.txt
Contents
version: STSv1
mode: testing
mx: mx1.hc5801-97.iphmx.com
mx: mx2.hc5801-97.iphmx.com
max_age: 604800

Set up a TLS report addressinstruction

Sending servers will report TLS failures when delivering to nginx.com, which you need before enforcing MTA-STS. The address must accept TLS reports; a DMARC report address does not necessarily do so.

Applies to: _smtp._tls.nginx.com

  1. Pick an address that will receive TLS reports: a mailbox you read (for example tls-reports@nginx.com, created first) or a TLS reporting service. 2. Publish a TXT record at _smtp._tls.nginx.com with the value v=TLSRPTv1; rua=mailto:<that address>.

Prepare BIMIinstruction

BIMI shows your logo next to messages in supporting inboxes, but only for mail that passes DMARC under an enforced policy.

Applies to: default._bimi.nginx.com

  1. Enforce DMARC first: p=quarantine or p=reject at 100% (no pct below 100). 2. Convert your logo to an SVG Tiny PS file and host it over HTTPS, for example https://nginx.com/bimi/logo.svg. 3. For Gmail and Apple Mail, obtain a VMC or CMC certificate for the logo. 4. Publish a TXT record at default._bimi.nginx.com with v=BIMI1, l= set to the logo URL and a= set to the certificate URL.