---
title: "How Do I Move Microsoft 365 Mailboxes When Changing Domains?"  
description: "How Do I Move Microsoft 365 Mailboxes When Changing Domains?"  
author: "Steven Miller"  
published: 2026-10-21  
updated: 2026-10-27  
canonical: https://www.mindstick.com/forum/162603/how-do-i-move-microsoft-365-mailboxes-when-changing-domains  
category: "computer"  
tags: ["database backup"]  
reading_time: 3 minutes  

---

# How Do I Move Microsoft 365 Mailboxes When Changing Domains?

When a company changes its business domain or moves to a newly created Microsoft 365 tenant, IT administrators often need to transfer employee mailboxes without losing access to important correspondence. This can happen after a merger, acquisition, company rebranding, or organizational restructuring.

One important point is that changing a user's email address is not the same as migrating a mailbox between tenants. If the organization is moving to a separate Microsoft 365 tenant, administrators need to plan the destination accounts, mailbox mapping, domain configuration, and data transfer separately.

Start by preparing a list of source mailboxes and their corresponding destination users. Confirm that the target accounts are created, the necessary Microsoft 365 licenses are assigned, and the required permissions are available in both environments. Also decide when the custom domain will be moved, since domain verification and email routing can affect the migration schedule.

Before transferring the mailboxes, review the following:

**Mailbox mapping:** Match each source user with the correct destination account.

**Email preservation:** Identify important messages, attachments, calendars, and contacts that must be transferred.

**Duplicate handling:** Check whether the target mailbox already contains some of the source data.

**Migration timing:** Plan a pilot and schedule the main transfer to minimize disruption.

**Validation:** Verify mailbox contents and email delivery after the change.

The **SysInfo** [**Microsoft 365 Tenant-to-Tenant Migration Tool**](https://apps.microsoft.com/detail/xpfpdrq0wml502)is designed to transfer mailbox data between Microsoft 365 tenants. It supports mailbox mapping, OAuth 2.0 authentication, selective migration, duplicate detection, and incremental transfers. Depending on the selected workflow, it can also migrate supported OneDrive and SharePoint data and Microsoft Teams components.

Keep in mind that mailbox migration does not automatically move every identity or domain configuration. Administrators should plan domain removal and verification, DNS changes, user sign-in updates, and mail routing as separate parts of the transition. Microsoft also recommends planning identity mapping and workload dependencies before a tenant-to-tenant migration.

A careful migration plan helps ensure that users can access their required emails in the new environment while the organization transitions to its new domain.

## Replies

### Reply by MailsDaddy Software

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Original Source: https://www.mindstick.com/forum/162603/how-do-i-move-microsoft-365-mailboxes-when-changing-domains

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