Often, your web server application won't know that the activation email can't be sent. It's common practice to throw outgoing emails into a job queue, so a very basic check isn't superfluous at all.
Yep, this is definitely most often the case. Perhaps I should have reworded that to reflect that I believe anything more than a simple /@/ check to be largely superfluous. I still use the /@/ regex often, which I mention at the end of the article.
