Many customers have multiple appliances. Prior to MEG 7.5, there wasn't really a good way to get all the mail traffic data and configuration settings handled from a single spot, however. Starting with MEG 7.5, ePO can now manage the configuration on MEG appliances directly through policy application. While this is a good thing normally, what happens when it comes time to deal with upgrades of varying sorts?
So the nutshell of the link between ePO and the MEG is that the ePO server has configuration policies which it then pushes down to the various attached appliances. Different policies can be pushed to different devices as desired. The question comes down to what needs to be done to address upgrades of various types.
So there's pretty much two types of upgrades which will be present for the appliances:
1. Upgrades which make changes to the configuration settings in various places.
2. Upgrades which simply update binaries and don't adjust configuration settings at all.
Version upgrades almost always fall into the first category. Many binary updates and configuration changes are present here and generally there are major changes to the appliance behavior.
Patches usually fall into the first category, although there are a few patches which may fall under the second. The number of patches which fall into the second category, however, is small.
Hotfixes are a much more mixed bag. Hotfixes frequently simply provide updates to binaries to fix some sort of vulnerability or significant errors. Sometimes, however, those binary fixes require changes to the configuration details for the appliance. In those cases, these fit into the first category.
So why the two categories? Because the attachment of the MEG to ePO requires the installation of MEG plugins and configuration uploads to the ePO. But what should admins do when updates become necessary? For all updates where the first category is true, it is absolutely necessary that customers follow the steps in KB79376. Failing to do so may result in unexpected operation or unexpected errors. For updates which fall into the second category, no changes are really necessary, so customers need not worry about following the steps in that KB. That said, however, since there's no indication on individual hotfixes or patches as to whether or not configuration changes are necessary, it's best to go ahead and run the steps found in the KB anyway, just to be sure that something like the GUI configuration doesn't get changed on the box but not in the configuration on the ePO server.