I am planning to get an unmanaged VPS. My question is what is required to send and receive email by my site which will be hosted on that VPS? Suppose I have a domain www.vpsboard.com which I got from some domain provider. I am hosting this domain on VPS which I got from company A. I assume I will have to install and configure mail server (looking for some good free mail server software) on my VPS to send receive email correct? Is there anything else required for e.g. buying service from some provider to relay emails or something!?