Hi, see this thread how to enable and issues around it ( appears to be some waiting time)
Your message wasn't delivered because the recipient's email provider rejected it / Enable-OrganizationCustomization.

Hello there,
I am trying to set up a PowerAutomate flow that will send an email when something is updated on an Excel spreadsheet. The flow works, only the email bounces with the following reason:
Your message wasn't delivered because the recipient's email provider rejected it. Remote Server returned '550 5.7.501 Service unavailable. Spam abuse detected from IP range.
When I am sending an email manually from outlook, the email gets through but not via Powerautomate. I have never sent emails from this email address apart for the past 2 days so I doubt it can be spam abuse.
As part as my investigations, I found an interesting thread on this forum suggesting that I should have a look at the Microsoft 365 Admin, under Policies & Rules > Threat Policies > Anti-spam polies and to change the setting on fowarding rules from 'Automatic - System-controlled' to 'On- Forwarding is enabled'.
But I am now getting a new roadblock as I am getting the error message:
*
The command you tried to run isn't currently allowed in your organization. To run this command, you first need to run the command: Enable-OrganizationCustomization
- I am not sure how to do that? Let me precise that we are a very small company so we don't have an IT guy to ask and I am the only 'admin' for the 365 account of the company, so I should have the right permissions to do it, but I'm not sure how.
Any help you could provide would be greatly appreciated