Migrate IMAP Mailboxes to Exchange Online & On-Premises

Himanshu Goyal Himanshu Goyal Updated On - 24 Jan 2019

Migrating from IMAP mailboxes to Exchange Online (Office 365) and Exchange Server (on-premises) has become a trend. Every organization is moving to Microsoft email servers because of their comprehensiveness and reliability. Also, Exchange provides better security for the critical data of an organization compared to web-based email servers. So, how IMAP to Exchange migration can be performed?

There are many IMAP email servers, and the process of migration is different for every IMAP account. For example, migrating Gmail to Exchange/Office 365 is different from migrating AOL emails to Exchange/Office 365. In this article, we’ll discuss how you can migrate IMAP mailboxes to Office 365 environment without any hassle. But, before going to that, there are some things that you need to know about IMAP to Exchange on-premises migration.

How Will the Migration Impact IMAP Users?

Migration of IMAP mailboxes to Exchange Server requires access to user mailboxes in the IMAP mail system. If you have the administrator credentials, then there won’t be any impact on other users until you shut down the IMAP email system.

However, if you don’t have access to user mailboxes, then you’ll have to reset the passwords. Resetting the password will allow you to access other user’s mailboxes. Also, other users won’t be able to use their IMAP mailboxes during or after the email migration. Once the migration is done without any disturbance, you can give access to users for their mailboxes.

Things to Know Before IMAP to Exchange Online Migration

As you know there are manual methods to migrate IMAP mailboxes to Exchange Online, but these methods have some limitations:

  • Users can migrate only emails and items in mail folders.
  • Maximum item migration limit for one user mailbox is 500,000.
  • You must have administrator credentials to migrate all the mailboxes.
  • Largest email size that can be migrated is 35MB.
  • You have to increase the connections to your email system to improve the migration performance.

How to perform IMAP to Exchange Online Migration?

Basically, there are different ways to migrate emails to Office 365 (Exchange Online) depending on the email client. For example, you can refer ways to migrate multiple email accounts to Office 365; but as we are talking about IMAP mailboxes, you can use PowerShell command to migrate IMAP mailboxes.

However, the manual methods are complicated and require a lot of time to migrate IMAP mailboxes. Also, there is no guarantee that all your mailboxes will be migrated to Exchange Online.

Migrate IMAP mailboxes to Exchange On-premises or Exchange Online (Office 365)

To avoid the hassles of migrating IMAP mailboxes to Exchange on-premises with manual methods, use Kernel IMAP to Office 365 tool. Also, it is one of the best tools to migrate IMAP mailboxes to Office 365 (Exchange Online). It is enhanced with some powerful features that include:

IMAP to Office 365

  • Migration of single/multiple mailboxes from IMAP email servers
  • Options to migrate archive mailboxes and public folders
  • Quick migration of multiple mailboxes using CSV file
  • Successful migration to Office 365, and different versions of Exchange
  • Incremental migration of IMAP mailboxes
  • Saves the entire migration report in CSV format.


Migrating IMAP mailboxes to Exchange on-premises or Exchange Online often becomes necessary for businesses. So, a reliable solution is crucial for this kind of migration. Kernel IMAP to office 365 is the best utility to perform IMAP to Office 365 migration.