I downloaded the new "important security update" as soon as ZA warned me to do so. I then installed it. My email software immediately lost its ability to communicate with my ISP's server. I checked the Zone Labs forums and discovered other users were having a host of problems with this update, and some of them were even having exactly the same issue as me. I uninstalled ZA, and re-installed the previous version. This immediately fixed my email problem. So my advice is to skip this update, and wait for the next one.