rspamd is my go to solution. Out of the box you get a lot of protection. I use Exim as my MTA but I suggest you use Postfix if you are starting from scratch, only because you will find a lot more write ups on it.
The biggest issue is getting an IP address which is not in the banned lists. IP reputation is key along with SPF and do not send spam!
In the UK a "business" static IP address is sometimes/usually/probably/might be OK. If you are unfortunate then it is already in the lists and you can check that out at point of sign up.
You might look into IPv6 too. I managed to do the Hurricane Electric IPv6 email thing on my home connection for a laugh. That was a few years ago. It seems I need to do something more to get to Guru status.
The biggest issue is getting an IP address which is not in the banned lists. IP reputation is key along with SPF and do not send spam!
In the UK a "business" static IP address is sometimes/usually/probably/might be OK. If you are unfortunate then it is already in the lists and you can check that out at point of sign up.
You might look into IPv6 too. I managed to do the Hurricane Electric IPv6 email thing on my home connection for a laugh. That was a few years ago. It seems I need to do something more to get to Guru status.