efax doesn't list "make" as a dependency, but actually uses it. This causes fax sending to fail on a system where make isn't installed. This occured on a 6.1 system. As far as I could test, it will also happen on 6.2.
This will be fixed in the next snapshot of Raw Hide (ftp://ftp.redhat.com/pub/rawhide/{arch}/RedHat/RPMS/).