If you are running Windows OS and are looking for a good, free email server, hMailServer is the best one out there. It is a free e-mail server for Microsoft Windows and supports all the common e-mail protocols (IMAP, SMTP and POP3) and comes with an easy-to-use COM library that can be used for integration with other software. It also has support for virtual domains, distribution lists, antivirus, antispam, aliases, distributed domains and much more. E-mail data is stored in a database server, MySQL or MS SQL, depending on your choice. It allows you to create email accounts for your domain. Everything that you need to do to setup a running email server, hMailServer provides them.
I was sure that I did not want to use IIS’ as an email server when I firsted started a project because it has limited features (as far as I know). Some things that I wanted to do like creating email accounts are not available, so I had to look for an alternative which meant looking for another email server that I thought had a crack (piracy! lol). Luckily though, hMailServer exists and I will be using this as the email server for all my other projects. It’s free! What more can you ask for.