Good Bad Helpers

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({

});

helpers.bad-mail-to.js

import Em from 'ember';

export function badMailTo(params) {
	let email = Em.Handlebars.Utils.escapeExpression(params[0]);
	let name = Em.Handlebars.Utils.escapeExpression(params[1]);

	return Em.String.htmlSafe(
    `<a target="_blank" href="mailto:${email}">${name}</a>`
  );
}

export default Ember.Helper.helper(badMailTo);

helpers.good-mail-to.js

import Em from 'ember';

export function goodMailTo(params) {
	let email = params[0];
	let name = params[1];
	let className = params[2];

	let a = document.createElement('a');
	a.target = '_blank';
	a.href = `mailto:${email}`;
	if(className !== undefined) {
		a.className = className;
	}

	let text = document.createTextNode(name);
	a.appendChild(text);
  
  return a;
}

export default Ember.Helper.helper(goodMailTo);

templates.application.hbs

<hr />
uses html safe:
{{bad-mail-to 'Alex' 'alex@gmail.com'}}

<hr />
no html safe:
{{good-mail-to 'Ben' 'ben@gmail.com'}}

twiddle.json

{
  "version": "0.12.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.12.0",
    "ember-template-compiler": "2.12.0",
    "ember-testing": "2.12.0"
  },
  "addons": {
    "ember-data": "2.12.1"
  }
}