If you have a local checkout of zcp and you've built the binaries without installing them system-wide, importing MAPI modules will fail. To get around this use:
$ fab zcp.load_local_zcp
This will do some magic on your system to make sure python can find MAPI and that the zarafa client can initialize correctly. It assumes this layout:
checkout: ~/zcp fakeroot: ~/fakeroot
For more info check fabfile.py