I have come across a bit of an issue that I'm hoping you experts can help me with. I have a batch of customers which have recently changed their internet connections to an ISP that has no SMTP relay on it's network. This is quite a big deal so I've decided to turn an old Exchange 2007 box into an open SMTP relay in my customers can use to relay mail out onto the internet. The plan is to have the SMTP relay at my offices for better control and this is on a different network/ISP altogether.
I have created an A Record smtp.domain.co.uk and pointed at our Public IP address so I'm guessing that's set up correctly.
Does anybody have any ideas on how I can achieve this? I do have a Public IP range for the customers networks so it doesn't have to be totally open as long as these public IP's can use our server as an smtp relay I can't see it being a problem.