Seems you are correct. Law must have changed in the last 7 years or so because the view was that an email was never proof of receipt while a letter and a fax where.
No. The view was that email was not proof of identity, it's relatively easy to spoof someone's account so if Real Madrid received an email from Ed Woodward, they'd have no guarantee that it was genuinely from him. Emails have had the facility to show whether a mail has been opened for some time now.
But i can't speak for the legal status: you were right that emails weren't recognised in law and I don't know what's changed but the issue was always about identity rather than receipt