Beta Key help

[StarCraft Poster]

I received an email with beta invitation yesterday, there is a cdkey inside, there are however 2 things i need answer to.1. How do i verify the email came actually from Blizz and it's not a scam, for that matter how do i confirm this key is valid?2. I already have linked Beta to my main profile, i wish to give this key to my mate but i don't want..

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