add support for transactional html/text emails

- Add support for welcome email on user creation (both OAuth and password users)
- Add support for html/text templating on verify email.
- Add support for html/text templating on reset password.
- Add handlers for converting Handlebars templates to HTML and text (template agnostic).
- Add helper function sendEmail() for compiling and sending templates via Email.send() (SMTP).

imports/api/Users/server/methods.js

@@ -5,7 +5,7 @@ import editProfile from './edit-profile';
 import rateLimit from '../../../modules/rate-limit';
 
 Meteor.methods({
-  'users.sendVerificationEmail': function usersResendVerification() {
+  'users.sendVerificationEmail': function usersSendVerificationEmail() {
     return Accounts.sendVerificationEmail(this.userId);
   },
   'users.editProfile': function usersEditProfile(profile) {

imports/api/Users/server/send-welcome-email.js

@@ -0,0 +1,25 @@
+import sendEmail from '../../../modules/server/send-email';
+import getOAuthProfile from '../../../modules/get-oauth-profile';
+
+export default (options, user) => {
+  const OAuthProfile = getOAuthProfile(options, user);
+
+  const applicationName = 'Application Name';
+  const firstName = OAuthProfile ? OAuthProfile.name.first : options.profile.name.first;
+  const emailAddress = OAuthProfile ? OAuthProfile.email : options.email;
+
+  return sendEmail({
+    to: emailAddress,
+    from: `${applicationName} <support@application.com>`,
+    subject: `[${applicationName}] Welcome, ${firstName}!`,
+    template: 'welcome',
+    templateVars: {
+      applicationName,
+      firstName,
+      welcomeUrl: Meteor.absoluteUrl('documents'), // e.g., returns http://localhost:3000/documents
+    },
+  })
+  .catch((error) => {
+    throw new Meteor.Error('500', `${error}`);
+  });
+};