You actually open email from unknown people/accounts?
If I snail mailed you a box with no return address on it, and it smelled funny and was making a mysterious ticking sound, would you open it?
Just wunderin...
I do not.
The author of this article is a journalist. His job requires him to open all mail from strangers that are not obvious bulk mail.
He or his system administrator should have installed a spam filter to get rid of the more obvious spam but there will still be a residue that he will want to look at himself.
People who use email for business open email from unknown senders all the time. It's not at all the same as a ticking box with no return address, it has an address, and it may be a potential customer.