Marco wrote:
> Can I send a custom SMTP error (ex. You must use an encrypted
> session!!), when exim4 reject an non-encrypted authentication session?
No. If AUTH was not advertised, Exim will say something like "AUTH not
advertised". But proper smtp clients will not use AUTH unless it was
advertised, so that's nothing to worry about.
If you want to tell people that you need TLS for AUTH, you could use a
custom smtp_banner, but few people will ever see (let alone read) it.