NDR
3 articles tagged NDR.
Fix 550 5.1.8 Access denied, bad outbound sender in Exchange Online
Why Exchange Online blocks a user with 550 5.1.8, how to secure the account first, and how to remove it from Restricted entities in the Defender portal or with Remove-BlockedSenderAddress.
Fix 550 5.4.1 Recipient address rejected: Access denied in Exchange Online
Find out why Directory-Based Edge Blocking rejects inbound mail with 550 5.4.1 and fix it for whole domains, hybrid recipients, public folders and dynamic groups.
Fix 550 5.7.30 Basic authentication is not supported for Client Submission
A printer, scanner or app stopped sending mail through Exchange Online with 550 5.7.30. Find the sender and move it to OAuth, High Volume Email or an SMTP relay connector.