I have 'multiple' questions here.

I need to implement a mail server on a windows 2000 box so the company I work for can share calendars in outlook. Is there any stipulation to the kind of mail server needed? If so what is that stipulation?
It needs to be applicable for both remote and local accounts, but I cant really see this being a problem (except on teh hardware side of things ;( ).

I was looking into Kerio mail serving software, as I have tried it out before. Would this be a decent mailserver for 25-50 people? Or is there a more elegant solution out there?

I need your opinions please!
EDIT
I seen clutch dug Exchange 2000/5.5 and this is also something that could be looked into. I am currently researching @ http://www.exchangeadmin.com/ I am kinda new to anything mail server!
/EDIT

i do know that exchange (previous to 2000) is a pain to setup on w2k server
exchange 2000 works very well

huh? Just install the latest SP and install 5.5 and away you go! Not a pain at all.

Well ... this really should have been in the 2k section E#%^(&*#$%

Sorry guys.

Jerry & DosFreak - thnx for the replies.

Im still looking into figuring out exactly what we need here ... so I guess the question was a little premature - but I think that exchange is definatly the way to go.

Exchange 5.5 and 2000 both work very well in Win2K, and would both meet your needs. Of course, the Exchange 2K license will be easier to obtain, and I would recommend getting software assurance as there should be an upgrade of Exchange in the next couple of years.

Well there is nothing to stop you buying Exchange 2000 licenses and then running Exchange 5.5 as MS licenses are downgradeable.
Personally I love Exchange 2000, I'm not saying it is a walk in the part setting up, configuring and looking after it, but as with most MS products the menus are very easy to follow and sinple trial & error will get most things up and running.
I've been running an Exchange 2000 server at work for coming up to 18 months now and it's been flawless except on one occasion.
One of my assistants noticed one of the partitions on the server was running out of space and he deleted some of the transaction logs - this was bad as the databases could no longer initialise.
But then again, a quick trip to MS Knowledge base and about two hours later I was back up and running.

Man, it was a MAJOR change in administration though. It took me 20 minutes to figure out how to create a damn account...

Exchange is cool.
why use 5.5 when you can have 2k.
it has less problems. but don't install on your file server or any server.
keep it in a seperate box.
it is the kind of animal that needs to be quarantined and backed up regularly.
if you stroke it just the right way it will make your life just a bit easier.