Occasionally, a customer needs a migration inside the Office 365 cloud platform. For example, if one company acquires another company and both are using Office 365, there may be many reasons to start merging. 

Our objective is to provide planning, design, and migration of email service from one Office 365 tenant to another. 

There will be some email downtime with this migration due to the time required to remove the domain on the Source tenant and add it on the Destination tenant. This is because Microsoft only allows the same domain to exist on one Office 365 tenant at a time. ​​Exchange Online Protection (EOP) can’t route email for the domain during the period of time when the domain is removed from the Source tenant and added to the Destination tenant, assuming the MX record is pointed at EOP. This results in senders getting a non-delivery report (NDR). Read the Move domains and settings from one EOP organization to another EOP organization TechNet article for options to queue email during this time

If short-term downtime and the possibility of losing some emails are not acceptable for you, please see another service Office 365 Tenant-to-Tenant Cutover Email Migration Without Downtime and Bounced Email .

IT Partner responsibilities

1. Export resources (mailbox-enabled users, contacts, groups, etc.) from the source tenant
2. Import resources to the destination tenant via AD Connect or CSV import
3. Do pre-stage migration (only emails and email folders older than 30 days)
4. Final mailbox migration with calendars, contacts, rules and other data
5. Change records in domain zones to accommodate migration needs

Client responsibilities

1. Provide a dedicated point of contact responsible for working with IT Partner
2. Coordinate any outside vendor resources and schedules
3. Configure all network equipment such as load balancers, routers, firewalls, and switches
4. If Microsoft Outlook or other desktop email clients are used to connect to Office 365, deploy email software on client workstations
5. Perform changes to internal and external DNS, as required
6. Assist with identification of high-risk users (top executives and VIP-users, users with 50 GB mailboxes or larger and/or 30 GB deleted folders or larger)
7. Recreate new Outlook profile on all client workstations, if desktop Outlook version is used
8. Inform users about upcoming changes and provide the necessary information

Additional cost items not provided by the project

1. Informing users about upcoming changes
2. Сustomer team training (could be added as additional service)
3. Migration of Corporate documents to SharePoint Online (could be added as additional service)
4. Desktop software settings

Upon completion of the project, we will provide a project closeout report. This document will indicate the final project status including evidence of matching acceptance criteria, outstanding issues and the final budget. If you require more extensive documentation, it can be provided for an additional fee.  

Prerequisites

1. You must have global-admin level access to the source Office 365 tenant
2. You must have global-admin level access to the destination Office 365 tenant with Exchange Online licenses available
3. You must have access to your email domain DNS zone

Plan

1. Kickoff meeting
2. Pre-migration source system health check
3. Creating users or configuring AD Connect tool
4. Email migration start
5. Verification of email migration
6. Changing MX record to new Office 365 tenant
7. Final email migration
8. Post-migration tasks

Success criteria

1. Users can access Exchange Online on their desktop PCs, mobile phones and tablets from any place, any time
2. Old Office 365 tenant successfully migrated to new Office 365 tenant and accessible by all users
3. All necessary Transport rules created and working
4. Mail can be sent and received using Exchange Online
5. Exchange Online Protection is configured and working