After an apparent successful install of IIS 6 & SMTP on Server 2012 R2, the IIS 6 snap-in is not listed when using MMC. Moreover, when attempting to load from the Server Manager menu, MMC throws a 'not able to create plug-in' error. There is very little in the Event Viewer and I have done this many, many times on other Server 2012 R2 installations. I can't seem to figure it out I've already done all the regsvr32 stuff I found references to as well as SFC & DISM. After several reboots, un-installs and re-installs, I've come to the conclusion I'm stuck.... Complete server re-build is not an option here.