title: Run a function user by user
body: <p>I want to run a function on each user.
  I know how to target a user logged in (<code>this.userId</code> client-side or <code>Meteor.userId</code> server-side) but not all the users - regardless they are logged in or not.</p>
  
  <p>The idea is to check if a <code>date type</code> field (<code>profile.Actu</code>), so in the profile user schema, is passed by more than 15 days. If yes, send a mail to a <code>profile.recipients</code> (also a field (<code>email type</code>) in the profile.user schema.</p>
  
  <p>Then I will run this function by a cron task, like every day, on each user, in order to check if that function must send a mail if the date (<code>profile.Actu</code>) is, that day, passed... Hope you understand the idea. </p>
  
  <p>Can anyone help me ? I'm very new to meteor, so my question may look naive... Thanks.</p>