I think there needs to be an act of publication for defamation law to be engaged though. It might be rather hard to argue that private emails reach that bar.

I'd note that the relevant definition of publish isn't the common-sense use (i.e. make available publicly), but merely "the communication of the defamatory matter to a third person" [0]. Indeed the first link in my prior post specifically calls out defamation via private methods of communication (texting) as something that may be actionable.

[0] http://www.hse.gov.uk/enforce/enforcementguide/court/reporti...

It seems like the reform act of 2013 might make these comments in-bounds:

Honest opinion: It is a defence for defamation, to show the statement complained of was a statement of opinion; that it indicated, in general or specific terms, the basis of the opinion; that an honest person could have held the opinion on any fact which existed when the statement was published, including any fact in a privileged statement that was pre-published. The defence is defeated if the claimant shows the defendant did not hold the opinion.

Before 2013 in the UK, not even truth was enough of a defense. Truths that caused harm (even justifiable harm) were still actionable.

In Austria it's still illegal to make true comments that offend religion sensibilities.

> Before 2013 in the UK, not even truth was enough of a defense.

Wasn't justification a different name for a truth defence?

The author of the article would have to be able to show that the comments caused serious harm, that they were published, and that they were defamatory.

The respondent would then have to prove, on the balance of probabilities, that the comments were either true, or fair comment, or privileged.

Defamation cases are very expensive to bring and a good outcome is not at all certain.