If email from your domain to Outlook.com or Hotmail is bouncing with AS9031519, check whether you have a valid DMARC record. Adding a basic record has stopped the rejection for some senders, but Microsoft’s support discussion also includes reports from domains with SPF, DKIM and DMARC already configured. A Microsoft Q&A moderator has described the broader delivery issue as a service degradation. Microsoft has not announced a new requirement for small senders.
Who the AS9031519 bounce affects
Reports on Microsoft Q&A involve mail to Outlook.com, Hotmail.com and Live.com addresses. Some senders say the same mail still reaches Microsoft 365 business accounts. That points to consumer mail, though Microsoft has not published a complete list of affected addresses.
That covers a lot of small Indian businesses. A clinic, CA firm or online store running Zoho Mail or Google Workspace on its own domain often still has customers on old Hotmail IDs. The same goes for website contact forms and WordPress order emails sent from your domain.
If you send from a free address such as @gmail.com, you do not control that domain’s DNS, so there is nothing to fix on your side. And if you are the one not receiving mail on Outlook.com, adding the sender to Safe senders will not help, because Microsoft rejects the message before it reaches your inbox. Forward the bounce to the sender instead.
The rejections are also intermittent. Some messages from an affected domain get through, and a resend can succeed, so one test email that arrives does not prove you are safe.
How this differs from Microsoft’s bulk sender rule
Microsoft already requires SPF, DKIM and DMARC from domains that send more than 5,000 emails a day to Outlook.com, enforced since May 2025. The new bounce looks different and reaches smaller senders:
| Bulk sender rule | AS9031519 bounce | |
|---|---|---|
| Who it hits | Domains sending 5,000+ emails a day | Small senders too |
| Since | 5 May 2025 | Reports from 5 Nov 2026 |
| Error code | 550 5.7.515 | 550 5.7.1 (AS9031519) |
| Shows which check failed | Can list SPF, DKIM and DMARC results | No |
| Public guidance | Published requirement | Moderator calls it a service degradation; no small-sender rule announced |
Microsoft’s support discussion includes reports of rejections even when SPF, DKIM and DMARC are configured. Adding a DMARC record is a sensible first step if you lack one, but it is not a guaranteed fix.
Step 1: Check whether your domain has a DMARC record
Run this in Command Prompt, PowerShell or a Mac or Linux terminal, replacing the domain with yours:
nslookup -type=TXT _dmarc.yourdomain.comIf the answer includes a line starting with v=DMARC1, you already have a record and can skip to Step 3. If it returns nothing, you need one. A domain must have only one DMARC record, because two records cause DMARC processing to fail entirely.
Step 2: Add a basic DMARC record
Sign in to wherever your domain’s DNS is managed, which is usually the registrar where you bought it or a service like Cloudflare. Add a new TXT record:
- Type: TXT
- Host or Name:
_dmarc(some hosts want_dmarc.yourdomain.com; check whether yours adds the domain automatically) - Value:
v=DMARC1; p=none; - TTL: the shortest option your host allows
The p=none policy asks receivers to take no DMARC-specific action on failing mail. It lets you publish a record without immediately rejecting your own legitimate messages. You can add a rua=mailto: reporting address later if you have a mailbox that can receive aggregate reports.
Zoho Mail admins can generate the record instead: open the Admin Console, go to Domains, pick your domain, then Email Configuration > DMARC. Choose “Do nothing to the emails”, add a report address, click Generate, paste the record into your DNS and click Verify.
DNS changes can take a while to show up. Zoho notes that a long TTL can stretch this to 12 to 24 hours, so run the lookup from Step 1 again before testing.
Step 3: Make sure SPF or DKIM lines up with your From address
A DMARC record alone does not guarantee a pass. DMARC passes only when SPF or DKIM passes and matches the domain in your visible From address. For SPF, that is the envelope sender domain; for DKIM, it is the d= domain in the signature.
The common trap is a third-party tool. A newsletter service, CRM or WordPress SMTP plugin may sign mail with its own domain, so DKIM passes but does not match yours, and DMARC fails. The fix is to set up custom DKIM for your domain inside that service.
To check, send a message to an account at another provider, open the full headers and look for dmarc=pass in the Authentication-Results line. Microsoft’s DMARC documentation maps out exactly how these alignment checks decide a pass or a fail.
Do not jump straight to p=reject
If you later tighten the policy, Microsoft and Zoho recommend moving slowly from none to quarantine to reject while you read the reports. With p=reject, any legitimate service you forgot to set up will have its mail rejected everywhere, not just at Outlook.com.
If bounces continue after your record checks out, resend the message, keep the full bounce text and pass it to your email provider. Microsoft’s forum moderators have asked affected senders to share bounce messages with Outlook.com support while the investigation continues.
Frequently asked questions
Do I need DMARC if I send fewer than 5,000 emails a day?
Microsoft’s published rule only covers bulk senders, but these bounces are hitting small senders too. A p=none record takes a few minutes to add and Microsoft says all senders benefit from it.
Will a p=none record stop my mail from being delivered?
No. It asks receivers to take no DMARC-specific action. Other spam filtering still applies.
I use an Outlook.com address and cannot receive someone’s email. What should I do?
Ask the sender to give the full bounce message to their email provider or administrator. The sender or their email provider needs to investigate the rejection.
How long before a new DMARC record appears?
Often minutes, but it can take up to a day with a long DNS TTL. A visible record does not guarantee that Microsoft will accept every message.
- SourceZoho Mail: DMARC policy
