No Universal Email is not compatible with DW CS6.
At this time, the only extensions we have that are compatible with DW CS6 are Design Extender, Data Bridge and eCart 5.
If you need to use Universal Email in DW CS6, I would strongly urge you to upgrade to Design Data Bridge which includes Universal Email and 12 other extensions.
we will be evaluating the stand alone extensions in the coming months for compatibility but with 30 extensions, it will take some time to go through them all.