Mail Server / Exchange Server

[Patton Echols]

Greetings all:

My 'buntu usage has been limited to my desktop and intranet / backup 
servers.  My questions concerns the real time difficulty of maintaining 
a mail server for a small organization.

First, once up and running, is the routine maintenance of a mail server 
particularly difficult or time consuming?

Second, <noob mode=elevated> The organization's current service limits 
the number of emails per day.  The service says "everyone does it that 
way"  If hosting ones own service, isn't it just a function of bandwidth?

Third, If my mail server is a virtual server in a data center somewhere, 
and serve mail out of it, does my server deliver mail through some other 
provider's server?  Or direct to recipients?  If the answer is "either" 
how does one decide?

Finally, the organization's mail is currently hosted on a  exchange 
server, but I am told that it is really only being used for mail.  Does 
anyone know what else an exchange server can do that is useful? and or 
is there a particularly "fine manual" that I should read?
</noob>

Thanks for any thoughts.

--PE