Exchange 2013 CU6 Outlook 2013

Some mailboxs setting in Message delivery restriction in EAC were automatically set up

checked the  only Auth user message. No body touched the setting,

Just seeing NDR just and understood the reason.

Any similar issues?

• Edited by tanale 22 hours 29 minutes ago

I really doubt and there is a very lean possibility of this setting getting changed automatically.

If you select the option require all senders are authenticated in Message delivery restriction then it will accept only emails from internal users and will not  accept emails from external users.

Also as an additional check you can perform an admin audit log search and check if any person with admin rights have changed this setting.

Hi tanale,

Thank you for your question.

If nobody modified it, you could check if there are any virus on Exchange server.

If all users mailbox is unchecked on Auth user message by default, we could refer to the following link to change auth use message into uncheck for all users:

Get-Mailbox |Set-Mailbox -RequireSenderAuthenticationEnable $false

If there are any questions regarding this issue, please be free to let me know.

Best Regard,

Jim