Replace email regex with EmailValidator gem dependency

[croaky]

I dislike the long, unreadable regular expression we use to validate the user's email. There are some nice EmailValidator gems out in the community. I did some research and I think this one is the nicest-written one:

https://rubygems.org/gems/validate_as_email

It uses the Mail gem as a dependency, which I like. I'd wager a guess that it's the most popular way to send email so I think we can feel good about depending on the Mail gem's parsing abilities.

One thing I'm not sure about is whether it's actually validating just the email part of the RFC spec or whether the Mail gem allows things like "Dan Croak dan@thoughtbot.com". I'm also not sure whether that's a bad thing. Need to play around a bit in a test app.

Would love some opinions from others.

[joshuaclayton]

Dan,

This looks pretty nice. Initial concerns were that it calls a private method to interact with Treetop (not horribly concerned, just hoping that the mail gem follows SemVer since his req in the gemspec is ~> 2) and that it hasn't been updated in more than six months (which is also somewhat bogus because it may be working just fine - there are no PRs or issues).

Out of curiosity, what other gems were you evaluating and what made them sub-par?

[jferris]

The validate_as_email approach does seem brittle. It calls a private method and then digs around internal structures to figure out if the address is valid. It also has a very loose version requirement. I'm pretty sure that will allow ANY version of mail, so the risk that you install a version of mail that doesn't work with validate_as_email seems high.

I wonder if there's a better way to interact with Mail::Address; I couldn't even find that class in the mail source.

[croaky]

Sounds like Treetop and using a maybe-not-public interface from Mail gem makes validates_as_email not as clean as I was thinking.

My second runner-up in my research was https://github.com/balexand/email_validator. It uses it a regex but has decent specs and is exactly the name I would expect this gem and related class (EmailValidator) to be.

[jferris]

email_validator looks good to me.

[croaky]

Opened PR #266 for this.