I'm a fan of Gray's Law: "Sufficiently advanced stupidity is indistinguishable from malice"
That is to say, if you "fuck up" bad enough, why should society give a shit that you did not have malicious intent? Much like drunk driving, I think that this is a fine case for strict liability.
What is the good you hope to accomplish by this? The reason we have the idea of intent encoded in the law is not because intentional acts are more harmful, but because inflicting severe penalties on people for things they can't even have known they were doing wrong or didn't mean to do is both contrary to the idea of justice and ineffective as a deterrent. The idea of throwing out the principle of mens rea just because the results of something were bad is both anti-utilitarian and contrary to the idea of justice. (Especially since the bar for "bad enough" is apparently low enough to include "not fastidiously keeping manually generated email archives". Jaywalkers beware!)
You may as well just say "Always attribute everything to malice whenever possible." Hanlon's razor is only necessary when both stupidity and malice are plausible explanations, so your "exception" applies 100% of the time. By this philosophy, we must always attribute deeds to malice whether or not they can be adequately explained by stupidity, because even when mere stupidity is sufficient, we must still read in malice.
> Never attribute to malice that which is adequately explained by stupidity, unless that stupidity is adequately explained by malice.
I'd like to coin this extension Hanlon's Exception.
[1]: http://en.wikipedia.org/wiki/Hanlon's_razor