Setup Server/E-mail as a Relay?

[Jeebs]

I have an Exchange server at home and I'm looking to use Sentora as the Smarthost/Relay to send e-mails through. I'm using a Residential ISP so sending mail through it isn't reliable. I wanted to test this route as I have a cheap VPS setup with Sentora and should have no problem sending e-mail from it. Going this route will allow me to keep my Exchange Server and route e-mails through the VPS/Sentora that's in the "cloud".

 I've played around with the Postfix main.cf and mynetworks config files but can't seem to get this working. I created an e-mail account within Sentora and I'm using that for the authentication so maybe that's not the way to do it?

Here's what I added in main.cf
mynetworks = 127.0.0.1, Sentora IP, MY ISP IP

Here's what I added in mynetworks
Sentora IP/28
127.0.0.0/8
MY ISP IP/32

[Me.B]

Either your use an for account authentification or white list your server IP for sending.

I'm not sure that your IP might not be blocking port 25?

So my advice check the logs to understand the error in your setup.