Actually you can. My mistake. Sorry about this. You can still send notes by mail, but only from the Menu bar Note > more sharing options; but not from the Share menu on the note itself. Again sorry for the false alarm. Moderators please delete this post.
EN 5.7 does not allow you to send a note by mail, period. You can send a link, which the recipient can open only after signing up to Evernote. In other words, it is nearly impossible to share a note directly by mail with people who do not use Evernote. Seriously? You guys think this is a good idea? If there were an Oscar for user-hostile behaviour, you guys would win it, hands down.