Migrate IMAP to Office 365 (Microsoft 365)

IMAP to Office 365 migration plan

Planning is one of the most important steps before you begin migrating your data to Office 365. Prepare the target environment and have a backup plan in place to avoid potential risks and data loss. Here is a brief checklist of points to consider before you migrate.

1. Take a complete backup of all the mailboxes, folders, calendars, contacts on the source server.
2. Remove unused mailboxes, mail items and duplicate files from the source.
3. Make an inventory of items before you make the move. These should include but are not limited to the following items.
   • User accounts, email addresses and login credentials
   • The source and target details, browser and operating systems used
   • Network settings, DNS configurations, MX records, firewall settings
   • Outlook settings and version you are using in your organization.
   • Licensing plans on your current source server
   • Active Directory configuration and other dependencies associated with it.
   • List of data and permissions from the source server that you want to transfer.
4. Determine the size of the data and number of mailboxes you want to migrate.
   • Decide if you want to migrate everything at once (cutover migration) or plan to migrate your data in stages (staged migration).
   • Decide if you plan to migrate to Office 365 Public folders, In-Place Archive, and Shared mailboxes along with the primary mailboxes.
   • Based on the preceding factors, estimate the approximate time that may take for the migration.
5. Create appropriate user mailboxes on Office 365 and assign licenses to them.
6. Ensure you have enough network capacity and bandwidth to migrate.
7. Consider the throttling and message size limits on Office 365.
8. Communicate the migration plan and changes to your end users and stakeholders.
9. Perform a test migration before you start the actual one.
10. Start the actual migration, verify the endpoints and update the MX records.
11. Check for correct mail flow and configure Outlook for all the users.
12. Plan for decommissioning unused apps and their settings post migration

Pre migration activities IMAP to Office 365 migration

On the source IMAP server

1. Ensure you have global administrator rights to migrate mailboxes from the source server. Assign the impersonation rights to the global admin to migrate mailboxes on behalf of users in your organization.
2. Take a complete backup of all your users data, configuration and messages
3. If you plan to migrate multiple users without the administrator login, prepare a CSV file with the list of all user mailboxes.
4. Find your IMAP server name and related connection settings.

On Office 365 :

1. Prepare your target Office 365 tenant. See tenant roadmap for Microsoft 365.
2. Assign the Organization Management role group in Exchange online to the admin user.This is an elevated role required to migrate Public folders.
3. Purchase a suitable Office 365 licensing plan. You can also sign up for a 30 day free trial and decide to go with a suitable one later. Compare Office 365 business plans and Compare Office 365 enterprise plans
4. Before migrating from IMAP server to Office 365, ensure that you create mailboxes for your users in your organization and assign suitable licenses to them.
   •  Add users and assign licenses to Office 365 users
   •  Add several users at the same time to Office 365
   •  Assign Microsoft 365 licenses to user accounts
5. If you plan to migrate to Public folders and Shared mailboxes on Office 365, ensure that you create and configure them on the target server.

    Create Office 365 Public folder and assign mailbox user

    Create Shared mailboxes on Office 365 and set the correct permissions

6. Ensure that the admin account on the target Office 365 server has the Application impersonation rights to migrate mailboxes and Public folders.
7. Check if the Global admin account with the management roles has a valid and non-hidden mailbox on the source and target server.
8. If you have a custom email domain to which you want to receive emails after the migration, you must add and verify the domain on Office 365.

    Steps to add a custom domain to Office 365 and steps to add DNS records to connect your domain.

9. Ensure that you meet the network and bandwidth requirements for the migration. See network and migration planning, performance factors and best practices for Office 365 migration.
10. Configure Office 365 to send and receive large messages.

     Follow the steps to increase the message size on Office 365 to 150MB. See message size limits on Office 365 for more information.

Post-migration tasks

Step 1: Update DNS records (MX record) to point to Office 365
If you have not done this step previously, change the DNS records known as MX records to enable and receive email messages on the target Office 365 server. In addition to this setup, configure the Autodiscover record to allow Outlook to connect to the migrated mailboxes.

Step 2: Create a new Outlook profile for users in the new domain
Remove any previous instances of the email account you may have on Outlook to avoid conflicts with Office 365. Configure and recreate the Outlook profile for each user in your domain after you complete the migration.

Migration troubleshooting

 See the migration troubleshooting guide for possible solutions related to common errors. For more information on EdbMails IMAP migration, see frequently asked questions (FAQs)

Benefits of EdbMails for IMAP to Office 365 migration

1. The application makes it simple to connect to the source and target servers directly and perform the migration.
2. With EdbMails you can migrate to Office 365 Public folders, Shared mailboxes and In-Place Archive.
3. Include and exclude filters enable you to selectively migrate emails based on Date, Subject, Attachment, Sender.
4. Folder options enable you to exclude mail folders such as Junk, Inbox, Drafts, Conversation History.
5. EdbMails is a highly secure tool and maintains a perfect data consistency between the source and target.
6. Supports migrations from/migrations to all IMAP enabled email servers.
7. The application is compatible with Windows 11, 10, 8.1, 8, 7 and all Windows server versions.
8. Free trial and free 24x7 customer support to help you with the migration.

 If you require further assistance, contact EdbMails 24x7 support. Try the free trial version today to start the migration!