Or, instead of copy/pasting regexes into each project (because I'm sure we have a slightly different email validation regex in Persona based on an earlier Gerv blog version), we could use some external module which does the lifting for us.

A few quick searches through npmsearch.com and you can find https://github.com/diasdavid/mailgun-validate-email or https://github.com/johnhenry/valid-email  or even just Joi's email validation: https://github.com/spumko/joi#stringemail