I am trying to create a mail server for inside an organisation with approximately 150 people, it doesnt have to be a mail server that sends out to the real world, can someone please point me in the right direction, i will be using Ubuntu Server 6.06 or Debian 4

Try http://www.qmailrocks.org

It's running my company and is lovely

I've got about 100 users distributed over Australia and New Zealand - this server ticks over nicely over a P4 / 1gig RAM / 76gb RAID 5

fukawi2, are you doing IMAP or just POP?

Default qmailrocks install does both pop3 and imap. I use it everywhere, it is a great mail setup. It handles spam and virus scanning (even better when you add in rbl lists from spamcop), and requires user authentication to send.

This uptime isn't even that good, we moved this server from one colo to another. I could easily see a server uptime reaching into 3-4 year range.

Peace,
JimBass

JimBass - that is more impressive. I had to shut mine down to rebuild our whole server room though

I was really trying to show the load average - your's is even a bit lower than mine

That server is running on 2 Intel III 1266 Mhz processors with 2 Gb of RAM. It's a Dell rackmount unit, and it behaves very well with hardware raid keeping it happy and healthy. It sees about 10,000 email messages in a typical day. When I posted that it was 9:45 am localtime, so the server had been getting hammered for the past hour by businesses. That server handles mail for all of our clients (we're a small ISP) who don't run their own mail. It probably has about 500 accounts on 20 domains, but only 100 or so of them are heavily active. True dual processors can drastically reduce loads well. Your P4 may have more processing power than both of my processors put together, but just having the ability to distribute the load keeps the averages low.

I would easily lose an uptime competition if one were to get started. My secondary DNS has an uptime of about 600 days, but I have seen BSD boxes (3 or 4 of them) on my coworkers old university with greater than 1000 days of uptime. Much like the duracell battery commercials from the old days, "they keep going, and going, and going." One easily could get the same results (long uptime) from linux, but it does take a bit more work. You do occasionally need to clear out things in /tmp, and keep the auto updater from grabbing a new kernel. Beyond that, any "server" that truly is a server (no gui, CLI only) really shouldn't have any issues staying up, given a battery backup. Most of the time one of our servers goes down it is either due to power loss (battery backup turns on and runs out) or the battery itself dies within a functioning unit, and you need to disconnect to replace the battery. When/if we know something like that will happen will drop a new kernel in before the reboot, but I have many boxes running like champs on old kernels, like the default 2.4.27 from Debian Sarge that have been up more than a year.

Peace,
JimBass

Absolutely JimBass - Power is what kills uptime

I've had my qmailrocks install since December, and I haven't had to shutdown / reboot it once apart from when power was going to be shutoff... Beats the heck out of my old 602Pro Lansuite on Win2000 mail server! I had to restart that at least 3 times a week

So in conclusion, we recommend http://www.qmailrocks.org