Agree. I'm not comfortable with the idea that seems to be taking hold on here that this ex boyfriend's email deserves the attention it's being given. And the doubt now being cast on HaB. I'm not here for that.
I'd personally need something way more significant than a solitary email from a potentially grudge-holding ex in order to feel vaguely comfortable about discussing a rape victim's credibility.
I doubt an email will be given any weight if the witness does not make themselves available to testify. It wouldn't even be admissible in the UK iMO