The distribution box is too high and obstructs access
Use the command Get-DistributionGroup | Format-List Name,MaxReceiveSize,MaxSendSize to view the size limit of sending and receiving emails for the distribution group and check whether the email you sent exceeds the limit. You can try the following methods to solve it: Try to resend the email without any attachments. This configuration has worked perfectly until I received a report about 2-3 months later indicating that someone without rights was still able to send an email. The complete NDR error message is as follows: Your message can't be delivered because messages to <recipients> are blocked by your organization using Tenant Allow Block List. These issues can include connection issues, sign-in problems, high latencies, or performance issues.
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