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How to Migrate Kerio to Office 365 Successfully? Best Ways

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Published By Jamie Kaler 
Rollins Duke
Approved By Rollins Duke
Published On April 28th, 2026
Reading Time 7 Min Read

In this guide, we will explain the best approaches to easily migrate Kerio to Office 365 using manual methods and Kerio to Office 365 migration tool. We will also cover some prerequisites, causes for migration and the practical ways along with pros and cons so that you can move your data with safety and smoothly without data loss.

Many users move from Kerio to Office 365 but are worried about complexity and losing data. As business grows, the data expands and need for Microsoft 365 increases which becomes a smarter choice to migrate Kerio to Office 365. So, read this article and understand what methods best to meet your expectations.

Why Migrate Kerio to Office 365?

Below are some of the common reasons that explain why users and businesses often look for this migration.

  • Kerio has limited storage which creates issues for users. Whereas Office 365 offers large storage capabilities and flexible plans to increase the limits.
  • Many users move from Kerio to Office 365 for better integration with tools like Microsoft Teams, SharePoint, OneDrive and workspaces.
  • Microsoft 365 offers strong protection against spam, phishing and ransomware threats unlike Kerio Connect.
  • Kerio is accessed on-premise whereas Office 365 can be accessed on cloud on any device.
  • Office 365 has an advanced and modern interface and ranks 3rd position out of 17 email applications.

Comparison: Kerio vs Office 365

Features Kerio Connect Office 365
Storage Depends upon server resources and often requires manual management. It offers large cloud storage features with multiple plans.
Security Kerio includes standard protection like anti-spam, antivirus and SSL support. O365 supports advanced security with MFA , encryption, Defender and threat protection.
Admin Controls Basic administration for users and server settings. Has a centralized admin center with advanced controls and policies.
Email Hosting Works on on-premises and self-hosted servers Fully cloud based and managed by Microsoft.
Collaboration Capabilities Support limited collaboration, email, contacts and calendars. It offers real-time collaboration with Microsoft 365 tools like Teams, SharePoint and more.
Maintenance It requires manual server management and upgrades. Microsoft handles its maintenance and automatically updates.
Work Support Basic support for remote access. Has a hybrid and remote work environment for seamless workflow.

Important Pre-Migration Steps

  • Review the number of mailboxes, shared folders, emails with attachments, contacts and calendars you have and need to migrate.
  • Make sure you have added and verified your domain in Office 365 so that email services work properly even after the migration.
  • Deleted unnecessary data to reduce mailbox size and speed up the process.
  • Ensure you have a stable internet connection.
  • Before starting with the method, keep yourself ready with the correct Kerio Connect and Office 365 account details.
  • First, test the process with a few emails. If it works then migrate the mailbox.

Related Article: How to Migrate Kerio Connect to New Server?

Manual Methods to Migrate Kerio Mail to Office 365

There are 2 manual ways using which you can perform Kerio Connect to Office 365 migration. Follow them carefully and select one as per your needs.

Method 1- Using IMAP Migration

  1. Login to Kerio Connect Administration Console.
  2. Go to Accounts > choose the user mailbox.
  3. Navigate to Configuration > Services. Select IMAP Service if not enabled before.
  4. Now, sign in to Microsoft 365 Admin Center.
  5. Go to Setup > Data Migration and choose IMAP.
  6. Create a new migration endpoint.
  7. Next, upload the CSV file that has your user mailbox data.
  8. Map Kerio Connect mailboxes to Office 365 account.
  9. Finally, start the migration batch. Office 365 will begin syncing emails.

Limitations:

  • In this method, users can migrate emails only.
  • This is a complex process as it requires technical configuration skills.
  • Shared folders will not be transferred.

Method 2- Migrate Kerio to Office 365 via Thunderbird

To continue with this method, make sure you have Thunderbird installed on your system. Now, let’s start with the steps.

  1. Open Thunderbird and go to Menu > New Account > Email.
    click on new account
  2. Enter your full name and Kerio email address.
  3. Now, choose IMAP and verify it by following the instructions it displays.
  4. Wait for Thunderbird to completely sync your Kerio mailbox.
  5. Once done, repeat the same steps to add your Office 365 account in Thunderbird.
  6. Next, when you can see both the accounts successfully configured.
  7. Select a Kerio folder > drag and drop it in the Office 365 mailbox.
  8. Perform the same to transfer all Kerio folders.

Limitations:

  • Users need to drag and drop each folder one-by-one.
  • This method is not suitable for users who have a large volume of data or multiple mailboxes.
  • Folder hierarchy may not be maintained in the proper way.
  • With this approach, installation of Thunderbird email client is required.

Best Kerio to Office 365 Migration Tool for Direct & Fast Process

The RecoveryTools Kerio Migrator is a perfect solution to directly migrate Kerio to Office 365 in a simplified way. It is created with a simple interface that enables both technical and non-technical users to effortlessly migrate an entire Kerio mailbox in less time and requiring no technical expertise. The tool maintains emails, contacts, calendars, tasks and other data in their original form without any alteration.

One of the biggest advantages of using this software is, it supports batch migrating mailboxes in a single go. Users simply need to add an Office 365 account and verify it with OAuth without having second thoughts about data security. To test the software, download it now and try its free demo version.

Download Now Purchase Now

How to Perform Kerio to Office 365 Migration in Minutes?

  1. Install and run the Kerio Mail to Office 365 Migration tool.
    run kerio to office 365 migration tool
  2. Load Kerio user’s mailbox data in the software panel using Select Folders and Select Files.
    add kerio emails
  3. Select I am converting Multiple Users option to migrate multiple Kerio user accounts.
    select i am converting multiple users option
  4. Check or uncheck the folders that you want to migrate.
    select loaded files
  5. Choose Office 365 from the saving options list.
    choose office 365 saving option
  6. The software will provide you with a Change language option to choose one as per your requirements.
    select a language
  7. Go to the Filter options tab and set them as per your needs.
    set filters
  8. Enter the Office 365 Email Address in the specific field.
    enter office 365 email ID
  9. Click Next to migrate Kerio to Office 365. The live progress of the conversion process is displayed on the screen.
    start kerio to office 365 migration

Major Highlights of Kerio to Office 365 Migration Tool

  • It supports direct Kerio to Office 365 migration without requiring any other application.
  • The utility is completely standalone that performs on the user system itself.
  • Using this, users can bulk migrate Kerio to Office 365 at once with no file size restrictions.
  • It provides multi-language support so that users can choose their preferred language for migration.
  • Offers a free trial version to allow test tool features before purchasing license key for unlimited conversions.
  • The software guarantees users that no data is lost and maintained in their original format throughout the process.
  • It will only ask for an Office 365 email address for Kerio to Office 365 migration and further verify your account with OAuth authentication.
  • Using this software, you can migrate all emails, contacts and calendars while saving time and effort.
  • It supports multiple filter options based on date range, from, to, subject and more. This helps to selectively migrate emails from Kerio to Office 365.
  • The Kerio Mail to O365 Migration tool is compatible with Windows 11, 10, 8.1, 8, 7, XP, and Vista for both 32-bit & 64-bit OS.
Conclusion

In this blog, we have learned manual as well as professional ways to migrate Kerio to Office 365. This migration helps users to improve collaboration and provides enhanced security. While manual methods are there, they come with multiple limitations and sometimes result in confusing processes. Whereas the professional trusted solution is safe and offers a direct way with complete data accuracy. The software will not store your login credentials and makes the conversion done in less time and in just a few clicks.

In addition, if you face issues related to working of the Kerio to Office 365 migration tool, then feel free to contact our support team either via Live Chat or draft a mail on [email protected].

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