title: Which library of spring should I use to send emails with multy-threading
body: <p>I have too many emails. I should write scheduler in order to send messages to them. Messages are different. I use spring framework 4.x. </p>
  
  <p>I can write simple  class, which connects to SMTP server. But in this case I should write my thread library too in order to send emails parallel. </p>
  
  <p>Do spring have already written library which give me more flexible way to do this tasks? I do not want to use threads. It will be nice if spring already have this functionality.</p>
  
  <p><strong>Do I need Spring integration for this?</strong></p>
  
  <p>Best regards,</p>