One of the recipients of these tawdry emails was a certain Charlie Whelan, erstwhile Gordon Brown chief thug (even the PLP couldn't stomach him) and currently Director of Politics at Unite where he is alleged to be something of a bad smell.
The emails went from the allegedly super-secure No. 10 email system to a fairly hostile, private email system, certainly used by, and possibly administrated by, people who are not impressed by this nonsense, nor those who instigated it. Since the Unite network is private and probably covered by one of the standard "fair use" policies, it is probable that, were this the source of the so-called "leaks", no law would have been broken, and they could effectively use the emails in any way they saw fit.
Why do people assume that because they know that one end of a communication conduit is secure, the other end must be?
I reckon there's a BOFL somewhere out there who has inadvertently done everyone a favour. He'll have to be more careful next time...