Install ExchangeOnlineManagement if it isn't yet installed (run as Admin):
Install-Module -Name ExchangeOnlineManagement -RequiredVersion 3.4.0

Import module:
Import-Module ExchangeOnlineManagement

Connect-ExchangeOnline -UserPrincipalName user@yourdomainhere.com
Enable-OrganizationCustomization


Install ExchangeOnlineManagement
https://www.powershellgallery.com/packages/ExchangeOnlineManagement/3.4.0


Enable Forwarding for all accounts:
Remote Server returned '550 5.7.520 Access denied, Your organization does not allow external forwarding. Please contact your administrator for further assistance. AS(7555)'. Please advise, this is a show stopper high priority ticket. Please escalate.
https://learn.microsoft.com/en-us/answers/questions/465091/how-to-enable-organization-customization
Connect-ExchangeOnline -UserPrincipalName youremailher@yourdomainhere.com
Enable-OrganizationCustomization
Set-HostedOutboundSpamFilterPolicy -Identity Default -AutoForwardingMode On
Get-HostedOutboundSpamFilterPolicy -Identity Default


Keywords: Microsoft Online Exchange Hosted, Email Forwarding, E-Mail, Rule