SMTP Server removed in Windows Server 2025

For reasons I dont fully understand, Microsoft decided some time ago to remove this feature. I suspect mainy because the SMTP server was pretty basic and did not so 'modern authentication'. Plus the cost of adding that in was probably not considered to be appropriate given the usage. SO many networking features have been added to NT the lost over the years. 

I have not found a simple smtp server to add into Windows Server that is free - and easy to use. But i have not searched all that hard! You could look here to see if any of the mentioned products would suit your needs: https://forwardemail.net/en/blog/open-source/windows-email-server

I suspect you may be better off spinning up a Linux VM and using something like OpenSMPD (https://github.com/OpenSMTPD). There are loads of servers available depending on your requirement.