Our users cannot send OOF replies to external customers. OOF has been setup via Outlook Web Access.
Screenshot of Exchange settings attached.
Outbound mail gets routed through Exchange Defender. I spoke to them and they told me to modify the Exchange Send server name to outbound-jr.exchangedefender.com, which i did.
Are you in the migration process of your Exchange to Exchange Online?
Be aware of customized solutions developed on the transport role on your old Exchange server. They might not be convertible to Exchange Online!
In migration, Powershell can be a very crucial tool to achieve success and finalize projects within deadline or even fix issues.
X500 or Legacy Exchange DN Attribute can cause lots of issue during the migration