You really can't blame Nedum for being upset with Cook, and Cook's behaviour over this affair didn't exactly place him in a good light. He had to resign (but there was a suspicion that this suited him).
But there was more to this than is realised. My memory is a little hazy on the exact sequence but I got involved by accident as I think I was a mod at the time and a poster (who was a good pal of Nedum's) put up some personal information about himself and the goings on that I didn't think he should have. So I contacted him and got the whole story (as he told it).
The offending email had actually been sent a year before the story broke and when you realise that, you realise there was more to it than a simple email going to the wrong person. Ned's family were very friendly with the Wright-Philips's, so Ian Wright knew Ned's late mum.
At the time the email was originally sent, Ian Wright was trying to get SWP a new contract at City so had no interest in rocking the boat. But once those talks broke down a year later, and it was clear there wouldn't be a new contract, he passed the story onto the media. He denied he'd been paid but I believe he was. However I also believe he passed it on to Mrs Onuoha, so he didn't benefit from it directly.
Anyway, the background got passed to the club and suddenly it all went quiet. I have some sympathy for Cook, who presumably pressed 'Reply all' instead of 'Reply' to Marwood's forwarding of the email from Mrs Onuoha, but his attempts to wriggle out of it, instead of just admitting his mistake and apologising, sealed his fate. You may well thin Ian Wright's part in this was a little cynical or you might think it was entirely justified. I can see both viewpoints and tend to think it was a bit of both.