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4.4.7 QUEUE.Expired: Microsoft 365 message expired

550 4.4.7Message expired in queuePermanent: retrying will not helpFrom Microsoft 365 and Outlook.com

Example
550 4.4.7 QUEUE.Expired; message expired

What it means

The message sat in an Exchange Online queue and every delivery attempt failed with a temporary error until the expiry time passed. Microsoft then stops and sends the NDR. The odd mix of a 550 reply with a 4.4.7 status reflects that: the underlying problem was temporary, but the outcome is final for this message.

The code alone does not tell you why delivery failed. The real reason is the last temporary error Microsoft received, so look at the NDR’s diagnostic details or the message trace. Common last errors are a greylisting reply, a timeout, a TLS failure, or a 4.7.x throttle from the receiving server.

Other expiry codes from Microsoft add the reason directly (5.4.316 for refused connections, for example). QUEUE.Expired is the plain version when the reason is just the last transient failure.

Likely causes

  • The recipient mail server was offline or unreachable for the whole retry window.
  • The receiving server kept throttling or deferring Microsoft’s IPs with 4xx replies.
  • TLS negotiation failed because a connector requires TLS and the remote certificate was invalid or expired.
  • A partner connector points to a smart host that no longer accepts the mail.

How to fix it

  1. Run a message trace in the Exchange admin center and read the last event detail for the message.
  2. If the last error was a timeout or refusal, test port 25 and the SMTP banner on the recipient’s MX hosts.
  3. If it was a TLS error, check the remote certificate and any connector that forces TLS or certificate validation.
  4. Recipient admin: if your server throttled Microsoft, raise the limits or allowlist Exchange Online’s outbound ranges.
  5. Resend once the cause is fixed.

Checks that apply

  • SMTP Diagnostics Connects to the recipient MX and shows whether it answers, offers STARTTLS, and presents a valid certificate.
  • TCP Port Test Quick test that port 25 is reachable on each MX host.
  • MTA-STS Check Checks whether the recipient published an MTA-STS policy that would make TLS mandatory and cause deferrals on a bad certificate.
See the example diagnosed

The classification runs without network lookups and we never store your paste.

FAQ

Why is a 4.x code in a final bounce?
The status describes the last temporary failure. The message expired while retrying, so the NDR is final even though the code starts with 4.
Should the sender just resend?
Only after the recipient side is fixed, otherwise the new copy will expire the same way.

Microsoft 365 delist portal Outlook.com SNDS

All 191 bounce codes