Here is how to add Send As permissions for a user, to a distribution list, in Powershell.
- First, connect to the 365 tenant.
Install modules if needed:
Set-Executionpolicy Bypass -Scope Process Install-Module PowerShellGet -Force -AllowClobber Install-Module ExchangeOnlineManagement -Force -AllowClobber
Connect to the tenant:
Connect-ExchangeOnline -UserPrincipalName adminuser@domain.com
- Then make the setting:
Add-RecipientPermission -Identity distgroup@domain.com -Trustee user@domain.com -AccessRights SendAs