Mail errors · Microsoft 365 and Outlook

What does “550; 5.7.515 Access denied, sending domain [SendingDomain] does not meet the required authentication level.” mean?

Outlook.com refused the message because your domain does not meet its sender requirements: SPF must pass, DKIM must pass, and DMARC must be at least p=none and aligned.

Last read from the sources at the foot of this page.

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The fix · DNS record
Type
TXT
Name
_dmarc
Value
v=DMARC1; p=none; rua=mailto:[email protected]
The first stage. Use your own domain and a mailbox someone reads.
01

What does it mean?

Microsoft set these requirements for domains that send more than 5,000 messages a day to Outlook.com, Hotmail and Live addresses. A message that does not meet them is refused with this code.

02

What exactly does the source say?

"550; 5.7.515 Access denied, sending domain [SendingDomain] does not meet the required authentication level."

03

Why would a small firm see it?

A domain with no DMARC record, or a service sending in volume that is not in SPF or not signing with DKIM for your domain.

04

How do I fix it?

  1. Start herep=nonereports only
  2. p=quarantinesuspicious mail to spam
  3. Where to aimp=rejectforged mail refused
Start: reports only
v=DMARC1; p=none; rua=mailto:[email protected]
Then: suspicious mail to spam
v=DMARC1; p=quarantine; rua=mailto:[email protected]
Then: forged mail refused
v=DMARC1; p=reject; rua=mailto:[email protected]
  1. Turn on DKIM signing for your domain at your mail provider, and at each other service that sends as your domain.Each one gives you a record to publish.
  2. Publish one TXT record named _dmarc with the p=none value shown here.Use a mailbox someone reads for the reports.

Keep one SPF record. Add the service inside the one record you have, before its last word, and keep every service already in it. A second SPF record makes the check fail for every message.

An SPF record may make at most 10 DNS lookups. Each include counts, and so do the includes inside it. Past 10 the check fails, so take out services you no longer use before adding a new one.

Use your own domain and a mailbox someone reads where the record shows yourfirm.example.

05

What else do the sources say?

we're announcing new requirements and best practices designed to strengthen email authentication for domains sending more than 5,000 emails per day.

At least p=none and align with either SPF or DKIM (preferably both).

If you exceed 10 DNS lookups, your SPF check might fail.

Sources

Where does this come from?

Related
07 · Check my firm

See what is open before anyone else does.

We read from outside, find each way in first, and show it with a check anyone can re-run. No access, nothing tested, no obligation.

What we readPublic sources only
Who sees itYou alone
Delivery72 hours from confirmation
Meeting firstNone
Reading requestPrivate
Problem: Enter your firm's name.
Problem: Enter your name.
Problem: Enter a full address, like [email protected].
Problem: That does not look like a website. Try yourdomain.com.

A person reads every request. Your outside reading comes by email within 72 hours from [email protected]. Privacy