There are many different Linux distributions. Some include support, and some have no formal support but have a user community that provides effective peer-to-peer support. The main Linux distributions are listed overleaf:
Red Hat Enterprise Linux: This is a commercial product. Payment for the product provides technical support for a limited time; further support is available on an annual contract basis. There are several products within the brand, and the lowest-specification product, Red Hat Enterprise Linux Desktop, is adequate for the purpose of an email gateway as long as single CPU PC is used. Installation can be made through a graphical installer and is very simple to perform. The Red Hat website address is http://www.redhat.com/software/rhel/.
Mandrake: This is the most popular Linux distribution, available for free, but users are requested to pay a small fee to support the distribution. This payment is required to access some parts of the Mandrake website...