How to point existing client to Exchange online (Office365)

Created by Abderrahim Ibnou el kadi, Modified on Fri, 18 Jun 2021 at 05:13 PM by Abderrahim Ibnou el kadi


Customers would like to change their hosted or on premise mail server to point to office 365 and would like to reduce the impact of mail interruption.


This document will focus on the steps to perform so that the users don't suffer from mail interruption while the move is in process. 

so before you start doing anything on the other side you must:

1- Login to your Proofpoint portal

2- To assure Email continuity, all users on proofpoint portal must be set as End Users, make sure they are all able to login to the portal. If this is not the case then:

  •  Make sure all the users are set as "End Users"
  •  If not select ALL the users 
  •  MASS UPDATE USERS button 
  •  Chose "End User" in the drop down menu next to "Role" 
  •  Click on "Update users" button.  (screen shots below) 

Note: that you can do the same process to set ALL users with "THE SAME"  password that they can change once they login.

3- Advise users that they can login to the portal using the link  <same as the one you, admin, is using to login> you will provide in the email

4- Require Users to change their Password

5- Let know Users to use their Emergency Mailbox

5- Navigate to Account management > Domains and Change the "Primary Delivery Destination" to point to a non valid IP i.e. (screen shot below) this way all messages will be held on the Proofpoint server. Screen shot1

6-  Wait for 1 hour for the change to propagate otherwise you might experience some bounce messages

7- Once the move is done you can then change back the "Primary Delivery Destination"  from to the new FQDN on office365 i.e. 
8- Wait 1 hour  then mail will start flowing directly to office365

9- to complete the set up correctly, please follow the instructions  from STEP2 to STEP6 on this KB
10- All messages in the Emergency mailbox will be cleared and users will be able to use their mail client in office365