Email delivered but the client receives NDR with error code 550 5.0.350
Article ID: 434438
Updated On:
Products
Issue/Introduction
Email security cloud displays an email as successfully delivered. The Track and Trace doesn't show up any issue. However, the sender receives NDR with error code: 550 5.0.350.
Environment
Email security cloud
Microsoft Exchange
Cause
The error isn't caused by Email security cloud but it is created by Microsoft Exchange.
5.0.350 is a generic wrapper that's used by Exchange Online for a wide variety of non-specific errors that are typically returned by the recipient's email organization.
Resolution
The error is created by recipient mail server and the query with the email should be addressed to recipient mail or security support. Also, it is recommended raising a case with Microsoft.
The issue with cause and troubleshooting is specifically described by Microsoft under Microsoft Learn Documentation.
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