I highly doubt the Blur email apps will work on Liberty, as they are dependent on a ton of Blur features and frameworks that have been stripped in this ROM.
Odd, as I have been able to install these on other ROMS that claim they are "blurless".
"blurless" is used any too many different ways. Truly "blurless" roms like LIberty, Rubix Focused, Fission, and Gummy (others?) built from an AOSP framework and use mostly apps compiled from source.
Others like Apex still start from the stock Moto Blur framework and then remove/tweak things to make it run faster/smoother. Since the basic Blur framework is still there, the blur apps still work.
You may want to look at "improved e-mail" in the market. It adds a handful of features to the stock e-mail client that make it a lot more appealing. I used it for quite some time and liked it (I use exchange e-mail). I was having some issues with it "locking up" and not receiving e-mails (had to force close it, then it would work fine again for awhile). Now, I'm just working with the stock e-mail client, but you may want to try it and see if it works well for you.
-Z
