Email Delivery has failed to these recipients

Question

Delivery has failed to these recipients or groups:

******@outlook.com.au

Your message wasn't delivered because the recipient's email provider rejected it.

Diagnostic information for administrators:

Generating server: MEYPR01MB7539.ausprd01.prod.outlook.com

******@outlook.com.au

Remote server returned '550 5.7.708 Service unavailable. Access denied, traffic not accepted from this IP. For more information please go to http://go.microsoft.com/fwlink/?LinkId=526653 AS(7230) [SY4PR01MB5563.ausprd01.prod.outlook.com 2026-03-28T12:50:51.209Z 08DE8CA0A57DC2C6]'

Original message headers:

Received: from MEYPR01MB7539.ausprd01.prod.outlook.com

([fe80::f8d9:91f7:376a:e86b]) by MEYPR01MB7539.ausprd01.prod.outlook.com

([fe80::f8d9:91f7:376a:e86b%3]) with mapi id 15.20.9745.024; Sat, 28 Mar 2026

12:50:51 +0000

MIME-Version: 1.0

Content-Type: text/plain

Date: Sat, 28 Mar 2026 12:50:51 +0000

Message-ID:

Can someone assist me in resolving this issue, as the Microsoft server is not accepting third-party IP settings? The third party is FYI Docs. https://fyi.app/

Answer 1

The error 550 5.7.708 Service unavailable. Access denied, traffic not accepted from this IP means the Outlook/Exchange Online service is intentionally blocking mail from the sending IP address (in this case, the third‑party service FYI Docs). This is equivalent to being on a blocklist/blacklist.

Because the block is on the recipient side, it cannot be fixed from the Outlook.com mailbox alone. The sending service (FYI Docs or its mail provider) must work with Microsoft to get the sending IP unblocked.

Use this approach:

1. Confirm the error is from Outlook.com
   • The NDR shows outlook.com and a 550 5.7.708 code, which indicates Outlook.com/Exchange Online is rejecting the connection from the sender’s IP.
2. Involve the sender (FYI Docs)
   • Share the full NDR (non‑delivery report) with FYI Docs support, including:
     • Error code: 550 5.7.708 Service unavailable. Access denied, traffic not accepted from this IP
     • The timestamp and the Microsoft server name from the NDR.
   • Ask FYI Docs to open a ticket with their mail provider or directly with Microsoft to review and delist their outbound IPs.
3. Typical remediation on the sender side
   • The sender’s mail system/IP is being treated as a spam source or otherwise untrusted. This is the same class of issue described in the Outlook.com guidance for errors that mention being blocked or listed:
     • The recipient’s server believes the mail server or account is a source of spam.
   • The sender (FYI Docs or its SMTP provider) must:
     • Check if their IP is on public blocklists.
     • Ensure proper SPF/DKIM/DMARC configuration.
     • Request removal/unblock from Microsoft using the process available to them as a sender.
4. Recipient‑side checks (limited)
   • Verify the recipient address is correct and active.
   • If other senders can mail the same Outlook.com address successfully, this confirms the issue is specific to the FYI Docs sending IP, not the mailbox.
5. If the problem persists for multiple senders or domains
   • Use Outlook.com support options to have the mailbox checked, but in this specific error scenario the fix almost always lies with the sending IP being unblocked by Microsoft.

In summary, this is not a configuration issue with the Outlook.com mailbox; the sending service (FYI Docs) must work with Microsoft to remove the block on its outbound IP.

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References:

• Sent email in Outlook.com comes back "delivery failed"