As a web hosting company running thousands of websites and even more email accounts, we are constantly battling spam. Usually the spam is incoming (sent to our customers), but sometimes our customers unknowingly send out spam.
Security is a double-edge sword. No one likes having the web site or email compromised, but you don’t like getting locked out by our security systems. To "resolve" this problem, we have implemented a new system to allow customers to easily (and automatically) unblock themselves.
Overall uptime for the month of October 2012 was 99.996%. 21 of 26 servers had 100% uptime.