If you’re looking for a free e-mail server. hMailServer is a good free open source e-mail server for Windows. It support all the common e-mail protocol (IMAP, SMTP and POP3) and can easily be integrated with many existing web mail systems. It has flexible score-based spam protection and can attach to your virus scanner to scan all incoming and outgoing email.
You can download and use hMailServer at no cost. Visit the link below for download.