Office 365 Sending Email from Alias Or Proxy Address Using PowerShell
Since July 2021, Microsoft enabled sending email from Alis or ProxyAddress you can simply enable this future by PowerShell or Using Admin Interface: Using Admin Interface: You can simply go to https://admin.exchange.microsoft.com/#/settings and then click on Mailflow-> Turn On Sending from Alias PowerShell: connect to exchange online then run this cmdlet: Set-OrganizationConfig -SendFromAliasEnabled $true