550 5.4.1: Recipient Address Rejected
Got "550 5.4.1 Recipient Address Rejected"? Microsoft documents this as an invalid recipient. Senders also report it on IP reputation blocks, which Microsoft does not document. One test tells you which.
Published · Last verified · Maintained by TamingDNS
550
5.4.1
Recipient Address Rejected
Very Common
🔢 Enhanced Status Code Breakdown: 5.4.1
| Component | Value | Meaning |
|---|---|---|
| Class | 5 | Permanent failure (Hard bounce) |
| Subject | 4 | Network and routing |
| Detail | 1 | Recipient Address Rejected |
Per RFC 3463 Enhanced Mail System Status Codes. Class (X) = severity, Subject (Y) = category, Detail (Z) = specific condition.
💬 What This Error Means
This code decides nothing on its own. Microsoft documents it as directory-based edge blocking rejecting a recipient address that does not exist in the tenant. Microsoft's NDR list also gives 5.4.1 a second meaning, Relay Access Denied: the server generating the error does not accept mail for the recipient's domain. Senders also report it with every authentication check green, but Microsoft publishes nothing that confirms a reputation path. One test tells you which recipient-side problem it is: send to a second, definitely-valid address at the same organisation. If only one address bounces, it is that address. If everyone there bounces, Microsoft's fix is for their admin to resync the accepted domain.
Common Causes
- The recipient address does not exist in the tenant, which is what Microsoft documents this code for
- The recipient domain is out of sync in Exchange Online, so valid addresses are refused
- Relay Access Denied: the server generating the error does not accept mail for the recipient's domain, which Microsoft puts down to a mail server or DNS misconfiguration
- Reported but undocumented: the receiving filters refusing your sending IP or domain, with SPF, DKIM and DMARC all passing
How to Fix This
- Send to a second address you know is valid at the same organisation. One address bouncing points at the address; every recipient bouncing points at the recipient domain being out of sync in Exchange Online
- Check the spelling of the recipient address, and ask their admin to confirm the mailbox exists
- If the whole organisation bounces, ask their admin to resync the accepted domain, which is Microsoft's documented fix. Only if that changes nothing, and SPF, DKIM and DMARC all pass, check your sending IP with our Blacklist Checker and the Microsoft delist portal
📚 Official Documentation
Microsoft attributes 550 5.4.1 "Recipient address rejected: Access denied" to directory-based edge blocking rejecting an invalid recipient, and its published fixes are all recipient-side. Senders also report the same code as an IP reputation block, but Microsoft documents no reputation path for it. Microsoft lists a second 5.4.1, Relay Access Denied, for a server that does not accept mail for the recipient's domain. Test a second valid recipient before assuming either.
📖 Microsoft 365 / Outlook documentation → Browse all Microsoft 365 / Outlook error codes →📋 Real-World Example Messages
These are real bounce message formats you might receive. Paste yours into the Bounce Decoder for instant analysis.
550 5.4.1 Recipient address rejected: Access denied [AM0P190CA0026.EURP190.PROD.OUTLOOK.COM]
🔗 Related Error Codes
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