Brand new M365 enviroment with Teams enabled. Problem is, that users cannot comment tasks. The comment first seems to be saved, but then user gets delivery error message into their Outlook and then the comment gets disappeared from the task. Error message in the Outlook looks like this;
Undeliverable: Comments on task "Can't comment on to-do tasks."
Delivery has failed to these recipients or groups:
EndpointManagement@xxx.xxx
Your message wasn't delivered because the recipient's email provider rejected it.
Diagnostic information for administrators:
Generating server: xxx.xxx.xxx.outlook.com
EndpointManagement@xxx.xxx
Remote Server returned '550 5.7.708 Service unavailable. Access denied, traffic not accepted from this IP. For more information please go to http://go.microsoft.com/fwlink/?LinkId=526653 AS(7230) [xxx.xxx.xxx.outlook.com]'
I am not exchange / Teams specialist, but I see that this seems to be the same problem as here. Any help?

