BibTeX, biblatex and biber ⇒ Biblatex: How to reference an e-mail

[postroutine]

Hello,

In a document I am writing, I need to talk about an interview I have done by e-mails.

I use Biblatex to manage my bibliography. On the Biblatex manual, I have seen that I can use the @letter or the @misc to record an e-mail.
But what field did I have to use ?


Best regards