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  1. Introduction
    1. Migration Tasks
      1. To Do
      2. Problems to Fix
      3. Research Tasks
      4. Known Issues

Introduction

When considering an Exchange Online to Exchange Online migration, This list is little older but though to post to use as reference :

By addressing these migration points systematically, organizations can ensure a smooth transition and seamless functionality during the Exchange Online to Exchange Online migration process.

Migration Tasks

To Do

  • Upgrade Clients to Office Pro Plus (M365 Apps)
  • Manual Mailbox Move Consideration.
  • Evaluate & Report Junk E-mails.
  • Change User/employee Provisioning Scripts to Make O365 Mailboxes
  • Assign Licenses to Employees and Contractors.
  • Shared Mailbox Migration approach.
  • Plan for updating/moving Exchange Documentation
  • Add all accecpted domains into O365.
  • UM Enable CSV Script
  • RBAC Roles in O365
  • Create Self Service Button for end users to initiate their mailbox migration.
  • Create a promotional email template for end users to enroll in migration activity.
  • Configure Prod Ready UM Dial Plans and Policies
  • Disable POP and IMAP for all Users
  • Get list of shared mailboxes that have sent emails in past 3 months
  • Get list of shared mailboxes with Forwarding enabled.
  • Add DDL as members of DLs in O365
  • Identify Users with Send As Permission
  • Convert Shared Mailboxes from User Type to Shared Resource Type
  • Remove the double authentication prompt for SSO while logging from external network
  • Sync discovery mailbox to cloud, this isn’t possible.
  • Verify and add O365 Proxy Email address for all users.
  • Sync UsageLocation for India Users, India doesn’t allow UM hence go for alternatives.
  • Sync All mail enabled users.
  • Sync Voice Mailboxes OU to O365
  • UM Policy Migration
  • EXO license Assignment
  • Block inbound e-mails from internet to @tenantdomain.onmicrosoft.com
  • Write-Back to On-Prem AD
  • Audit and Reduce Voicemail Boxes

Problems to Fix

  • AD Pictures don’t sync to cloud.
  • Legitimate emails being marked as SPAM
  • Forwarding back to on-prem not working
  • Conf rooms don’t appear on room list after migration to cloud
  • Exchange Data in Puerto Rico
  • OWA Redirection for on-prem owa url no longer works
  • O365 Mailbox can’t open On-Premise Mailbox through OWA
  • disable popup for autodiscover certificate Outlook
  • Retention Policies Not Following Migration
  • Dynamic DLs doesn’t include O365 Mailboxes

Research Tasks

  • Test Riverbed WAN Acceleration with O365.
  • Monitor Pending Messages Queue in Office 365 or enabled alerting.
  • See use of Accepted Domains on-premise to be changed to Internal Relay
  • How to migrate Online Archive back to Primary Inbox.
  • Graph API
  • How to synchronize Voice mail PIN.
  • Test 2-factor capability for all Client Types.
  • Test Mailbox Permissions in Cloud when Granted through DL or Security Group

Known Issues

  • Lync integration of owa doesn’t work in Office 365.
  • Calendar delegation does not work across onprem/cloud
  • Activesync username must be changed to UPN
  • You cannot edit DLs through Outlook once you move to cloud
  • Android Clients Need to be deleted and recreated
  • Unable to enable UM for single user
  • Can’t give full access to an on-prem mailbox when user is in cloud

Thank you for reading and I will update the doc to more modern approach.