If you're new to running a mail server or linux server, then yes, lots of troubleshooting, etc... If you have someone who knows what they're doing, it's really

If you're new to running a mail server or linux server, then yes, lots of troubleshooting, etc... If you have someone who knows what they're doing, it's really not a big deal. I don't think I've had to spend any time on any of my mail servers in ages. Not sure what you mean by additional storage? Local corporate e-mail might take up ~10GB per person after a few years? Most of my servers have 1+ TB of local storage + SAN. Takes a lot of e-mail to fill that up. Spam and malware filtering are both pretty easy. yum/apt-get install clam and/or spamassissin/razor/pyzor/whatever. If you're running your own server(s) anyhow then backups, user admin, etc... are a sunk cost you've already spent. If you're running your own servers anyhow, it's really not a big deal. I have a normal GMail account and a enterprise google apps account and both of them have pretty frequent IMAP outages (usually just for 5-15 minutes, nothing serious) whereas my mail servers haven't been down in years (minus planned server migrations). Also, if something does break, I like being able to go in and fix it, without waiting for other people.