office365.com
Good, with 2 things to fix
office365.com scored 80/100 (grade B). The main issues are no DKIM key found for the common selectors and MX: mail relies on implicit A record. Detected senders: Microsoft 365.
Checked 2026-10-04 02:03 UTC · fresh check
All checks
MXCan servers find your inbox?Mail relies on implicit A recordNeeds attention
- Warning: Mail relies on implicit A record
office365.com has no MX records, so senders fall back to its A/AAAA address (RFC 5321 implicit MX). Publish an explicit MX record, or a null MX ("0 .") if the domain should not receive mail.
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?No DKIM key found for the common selectorsNeeds attention
- Warning: No DKIM key found for the common selectors
None of the 47 selectors probed under office365.com publish a DKIM key. DNS cannot list selectors, so a key under a custom selector may exist: find the s= value in the DKIM-Signature header of a message you sent and check that selector. If DKIM is not set up, enable it at each service that sends mail for office365.com.
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.office365.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?MTA-STS is in testing modeInfo
- Info: MTA-STS is in testing mode
Senders report TLS failures (with TLS-RPT) but still deliver. Switch to mode: enforce once the reports are clean.
TLS-RPTWill you hear about failures?No TLS-RPT recordInfo
- Info: No TLS-RPT record
No TLS reporting record at _smtp._tls.office365.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
Enable DKIM for Microsoft 365instruction
Microsoft 365 generates the DKIM key for each account, so the exact record must come from Microsoft 365. Without DKIM, mail it sends for office365.com cannot pass DMARC through DKIM.
Applies to: selector1._domainkey.office365.com
- In Microsoft 365, enable DKIM signing for office365.com: tenant-specific: copy Selector1CNAME/Selector2CNAME from Microsoft 365 Defender > Email authentication > DKIM. Publish exactly the record Microsoft 365 shows (TXT or CNAME) at the host name it gives, then turn signing on. Instructions: https://learn.microsoft.com/microsoft-365/security/office-365-security/email-authentication-dkim-configure
Enable DKIM for Microsoft 365instruction
Microsoft 365 generates the DKIM key for each account, so the exact record must come from Microsoft 365. Without DKIM, mail it sends for office365.com cannot pass DMARC through DKIM.
Applies to: selector2._domainkey.office365.com
- In Microsoft 365, enable DKIM signing for office365.com: tenant-specific: copy Selector1CNAME/Selector2CNAME from Microsoft 365 Defender > Email authentication > DKIM. Publish exactly the record Microsoft 365 shows (TXT or CNAME) at the host name it gives, then turn signing on. Instructions: https://learn.microsoft.com/microsoft-365/security/office-365-security/email-authentication-dkim-configure
Set up a TLS report addressinstruction
Sending servers will report TLS failures when delivering to office365.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.office365.com
- Pick an address that will receive TLS reports: a mailbox you read (for example tls-reports@office365.com, created first) or a TLS reporting service. 2. Publish a TXT record at _smtp._tls.office365.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.office365.com
- 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://office365.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.office365.com with v=BIMI1, l= set to the logo URL and a= set to the certificate URL.