email delivery error (450 4.4.317)

[neonetman]

Since removing our Edge server and re-routing our firewalls to point incoming mail traffic at our main Exchange server, any email destined for on-premises mailboxes is sitting pending with the following error

 

[color=#000000][font=&quot]Reason: [{LED=450 4.4.317 Cannot connect to remote server [Message=UntrustedRoot] [LastAttemptedServerName=mail.*******.org.uk] [LastAttemptedIP={our ip}:25] [LO2GBR01FT003.eop-gbr01.prod.protection.outlook.com]};{MSG=UntrustedRoot};{FQDN=mail.********.org.uk};{IP={our ip}};{LRT=2/24/2021 10:21:05 AM}]. OutboundProxyTargetIP: {our IP}. OutboundProxyTargetHostName: mail.********.org.uk

 

I'm at a loss what the issue is now. Can anyone help?

 

 

[/font][/color]

[bald_pig]

Is the connector on 365 still expecting the edge server?

[chaplic]

More like the exchange server is offering up an non-public cert as part of the connection