Just installed ClearOS on a PC to act as our firewall firstly and then to act as an internal mailserver.
My question is: Can i create a mailserver that then routes the mail through to our ISP mail server without having to contact the ISP and gain MX records etc..?
We are a small business (5 PCs + dataserver) and the reason this is interesting is because we need to keep a record of outgoing mails from certain users, as well as spam and virus filtering.
Best Answer
You users need to have YOUR server as the outgoing smtp server, your server will then handle the relaying to the upstream at the ISP. When it does this the server will scan the messages before handing them over to your ISP smtp. You should not allow port 25 outside of your network in the firewall. If you do, then you could open up for outbound spam. If one of your machines on the network got a virus or something it could mail directly out.