Yes, Starkit is a full scale mail server (among many other functions). You can add your domain names and create email accounts for you and your employees at your domain.
By adding a domain on Starkit:
a) You can easily create email accounts for you and other people in your organization at your domain (i.e. firstname.lastname@example.org), through a simple administration screen, without requiring the help of an IT professional.
b) You will no longer need to maintain your in-house mail server or pay fees to your current email service provider (i.e. Google Apps or Hosted MS Exchange services).