Can one of the admins verify this patch? To accept patch and trigger a build add comment ".ok\W+to\W+test."

Thank you for the pull request. It looks is v3 of isemail does not work in the browser out of the box and thus it's breaking out tests verifying LoopBack functionality in browser (see the failed CI builds on Travis CI). In order to land this PR, we need to find a way how to make isemail work. It may be enough to tell browserify to ignore certain dependencies when creating the browser bundle, see the current config:

On the second thought, it's also possible that the new version of isemail is using modern JS constructs from ES6+ that are not supported by PhantomJS that we use to run our tests in the browser. This could be solved e.g. by adding Babel transpiler to our test setup or by switching from PhantomJS to Chrome Headless (or Firefox Headless). Either way, such change should be ideally made in a new pull request, or at least in a standalone commit clearly separated from the is-email update.

The Karma test failures may be unrelated to the changes made in this pull request, see #4252

I checked out this feature branch and run the tests locally, unfortunately they are failing with the new isemail version (while passing with the older version).

PhantomJS 2.1.1 (Mac OS X 0.0.0) ERROR
 TypeError: undefined is not a constructor (evaluating ''0円'.normalize('NFC')')
 at /var/folders/ht/v2sc3fbn5m77w03kybtbf6h40000gp/T/0d4a49f78735968e521f5df205d36d0c.browserify.js:67609:48
PhantomJS 2.1.1 (Mac OS X 0.0.0): Executed 0 of 0 ERROR (0.404 secs / 0 secs)
PhantomJS 2.1.1 (Mac OS X 0.0.0) ERROR
 TypeError: undefined is not an object (evaluating 'ACL.WRITE')
 at /var/folders/ht/v2sc3fbn5m77w03kybtbf6h40000gp/T/0d4a49f78735968e521f5df205d36d0c.browserify.js:174236:31
PhantomJS 2.1.1 (Mac OS X 0.0.0): Executed 0 of 0 ERROR (0.406 secs / 0 secs)
PhantomJS 2.1.1 (Mac OS X 0.0.0) ERROR
 TypeError: undefined is not an object (evaluating 'loopback.Checkpoint.extend')
 at /var/folders/ht/v2sc3fbn5m77w03kybtbf6h40000gp/T/0d4a49f78735968e521f5df205d36d0c.browserify.js:172675:37
PhantomJS 2.1.1 (Mac OS X 0.0.0): Executed 0 of 0 ERROR (0.407 secs / 0 secs)
PhantomJS 2.1.1 (Mac OS X 0.0.0) ERROR
 TypeError: Object is not a constructor (evaluating 'it')
 at /var/folders/ht/v2sc3fbn5m77w03kybtbf6h40000gp/T/0d4a49f78735968e521f5df205d36d0c.browserify.js:170898:7
PhantomJS 2.1.1 (Mac OS X 0.0.0): Executed 0 of 0 ERROR (0.407 secs / 0 secs)

Rebased on top of the latest master to apply the CI fix from #4262.

Landed, thank you for the contribution! ❤️