title: Remote Server returned '550 5.1.10 RESOLVER.ADR.RecipientNotFound; Recipient not found by SMTP address lookup'
body: <p>I have an exchange server 2016 and I've created a user, say testuser1@exchangedomain.com</p>
  <p>I followed the steps as told in this video:
  <a href="https://www.youtube.com/watch?v=GN2mZ6qOWf8" rel="nofollow noreferrer">https://www.youtube.com/watch?v=GN2mZ6qOWf8</a></p>
  <p>I'm trying to send a mail from testuser1@exchangedomain.com in the exchange server to any outlook account in the outside world, for example, username@outlookdomain.com</p>
  <p>But I'm unable to send a mail from testuser1 and I'm receiving this error on the exchange server
  Remote Server returned '550 5.1.10 RESOLVER.ADR.RecipientNotFound; Recipient not found by SMTP address lookup'</p>
  <p>Is it even possible to do so because both the domains are completely different or am I missing something here?</p>