| stapf | Office 365 | heidelberg.asta | |||||
| Action Required | Recipient | ||||||
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| Unknown To address | |||||||
| How to Fix It |
| The address may be misspelled or may not exist. Try one or more of the following: |
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More Info for Email Admins
Typically this error occurs because the recipient email address is incorrect or doesn't exist at the destination domain. This can usually be fixed by the sender. However, sometimes the issue needs to be fixed by the recipient or the recipient's email admin. If the steps in the How to Fix It section above don't fix the problem, and you're the email admin for the recipient, try one or more of the following:
The email address exists and is correct - Confirm that the recipient address exists, is correct, and is accepting messages.
Synchronize your directories - If you have a hybrid environment and are using directory synchronization make sure the recipient's email address is synced correctly in both Office 365 and in your on-premises directory.
Errant forwarding rule - Check for forwarding rules that aren't behaving as expected. A forwarding rule can be configured by an admin via mail flow rules or mailbox forwarding address settings, or by the recipient via the Inbox Rules feature.
Mail flow settings and MX records are not correct - Misconfigured mail flow settings or MX records can cause this error. Check your Office 365 mail flow settings to make sure your domain and any mail flow connectors are set up correctly. Also, work with your domain registrar to make sure the MX records for your domain are configured correctly.
Mail loop detected - This error also indicates that the receiving organization's email settings are misconfigured, creating a mail loop when a message is sent to an address that isn't found in their directory. This usually won't disrupt mail flow for recipients that actually exist, but the recipient's email admin should fix the misconfiguration to reduce the chance of any other mail flow issues. A common cause for this loop is that the recipient's domain is configured as "Internal Relay" when it should be "Authoritative." Another common cause for the loop is that both the sender and recipient are part of the same organization, but the sender's mailbox is hosted by Office 365, while the recipient's mailbox is hosted on-premises, and an outbound connector from Office 365 to the on-premises email servers is missing or misconfigured. To fix this, the recipient's email admin should create a correctly configured outbound connector in Office 365 to route the message to the on-premises mailbox.
For more information and tips to fix this problem, see Fix email delivery issues for error code 5.4.14 in Office 365.
| Created Date: | 7/6/2025 10:55:44 AM |
| Sender Address: | stapf@zapf.in |
| Recipient Address: | heidelberg.asta@stud.hs-fresenius.de |
| Subject: | Resolution zu Verwaltungsgebühren an Hochschulen |
Error Details
| Error: | 554 5.4.14 Hop count exceeded - possible mail loop ATTR34 [BE1PEPF0000056C.DEUP281.PROD.OUTLOOK.COM 2025-07-06T10:56:22.708Z 08DDB901901E8EAC] |
| Message rejected by: | BE1PEPF0000056C.mail.protection.outlook.com |
Notification Details
| Sent by: | DB9P251MB0569.EURP251.PROD.OUTLOOK.COM |