It’s not just spam. It’s not just phishing. Although both would be enough reason to go with a more whitelisted, mobile, terse, collaborative communications solution than email.
There’s also trolling as best seen done by the funny and offensive E-mails from an asshole at DontEvenReply.com
Of course, it’s NSFW at most places of work.
Be brave. Be steadfast. Be sane. Don’t even reply. Or better just go #noemail.