Hi @TA.Saurabh.Singh ,
In order to better solve this issue, I want to confirm the following points:
- Does only one user have this issue, or does all users in the organization have?
- Will you receive the NDR only if you send an email with an attachment? Have you ever tried an email without attachments?
- Reply to this message with OWA to see if the issue persistent?
According to my research the error information, there are many possible causes of this issue, please try to following the steps and see if it has any changes: - Please try to run “outlook /safe” in the Run to start outlook as safe mode, To avoid interference from third-party Add-ins.
- To avoid version impact, it is recommended that you upgrade the Outlook client to the latest and then try again after creating a new profile.
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