title: Is it safe to send Paypal transaction ID to buyer via email?
body: <p>I'm creating an e-commerce shop using Paypal Express Checkout payment. Inside IPN callback, after <a href="https://developer.paypal.com/webapps/developer/docs/classic/ipn/integration-guide/IPNIntro/" rel="nofollow">required checks</a> I send a confirmation email to buyer. Inside this e-mail I would like to include Paypal transaction ID, to let user easily communicate with vendor about order, if necessary. </p>
  
  <p>Is it safe to send Paypal transaction ID to buyer via email?</p>