title: troubleshoot hybrid office 365 and regular email system - bounced emails
body: <p>A client is using office365 for only one of his emails. The rest of the emails run off the server with exim4 of the same domain name. There are two MX entries, one is for office365 and the one is for the domain.com. If I add both the correct settings and give the office 365 / outlook mx entry highest priority, all non office365 user emails get bounced because office365 / outlook does not recognise the emails. If I set the priority the other way around, all emails work, but the office 365 email fails. There are some changes I made to exim4 configuration based on office365 documentation, but this did not solve the issue. It's something stupid I am missing. I need somebody who knows what he / she is doing and can fix this quickly. </p>
  
  <p>The address you sent your message to couldn’t be found at the destination. It might be misspelled or it may not exist. Try to fix the problem by doing one or more of the following:</p>
  
  <pre><code>Retype the entire email address manually and resend it – if your mail program automatically suggests an address to use don’t accept it.
  Contact the recipient by some other means (by phone for example) to confirm you’re using the right address. Also ask them to check that that any mail forwarding they've set up is working correctly.
  Clear the recipient nickname cache in your mail program by following the steps in this article: Status code 5.4.14 in Outlook.com and Office 365. 
  </code></pre>
  
  <p>To clarify further, boss@thatdomain.com is an office365 email addy, but worker1@thatdomain.com, worker2@thatdomain.com etc. are normal emails that run direct on EXIM4 and dovecot. Operating system is Ubuntu I think, with VestaCP. The DNS is managed on dyn.com.</p>
  
  <p>I have posted a project on a freelance site, and if there is somebody who can solve this, I will gladly pay for the effort. I know it's a matter of the correct setting in exim4 config file or something, but I just can't get it to work.</p>