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Bulk Import MBOX to Kerio Mail Server Precisely: Complete Guide

  Mark Regan
Mark Regan
Published: April 30th, 2026 • 5 Min Read

Summary: You can import MBOX to Kerio mailbox for free using an email client like Thunderbird (instead of Kerio Webmail) or at the server level by converting MBOX files to a Kerio-compatible format. Using BitRecover MBOX to Kerio converter is a direct way for bulk import without technical complications and ensuring complete data integrity.

Table of Content Hide
  1. User-level Thunderbird method
  2. Server admin approach
  3. Professional solution
  4. Method comparison
  5. Support information

Why Transfer MBOX to the Kerio Connect Server?

Kerio Connect is a widely used email server across industries. It is compatible with all Linux, Mac & Windows devices with access via Webmail. There can be various reasons why users import MBOX to Kerio Mailbox:

  • Multi-device access via Webmail
  • Reduced risk of bulk corruption (due to its individual-level email storage)
  • In case of account centralisation or to restore the MBOX backup into the Kerio Mailbox.
  • The common reason why a user imports MBOX files into a Kerio account is the case of email service migration.

This guide offers step-by-step instructions to access MBOX data in Kerio Connect mailboxes without data loss, both at the server admin and user level.

Method 1: Import MBOX to Kerio Mailbox Using Thunderbird

This method lets you add MBOX files to Kerio accounts even at a user level. It is a free, non-technical way – that is often also adopted by the server admin for small-scale MBOX to Kerio Connect Migrations.

Disclaimer: Migration via Thunderbird will only work if you are using IMAP with the Kerio Connect server.

Pre-Requisites:

  • Mozilla Thunderbird application
  • Kerio Mailbox User ID and Password
  • IMAP server details (Ask Admin or View in Webmail Settings)
  • Stable internet connection
  • Ensure your mailbox has free allotted space on the MBOX file.

Steps to Transfer MBOX to a Kerio Connect Account

  1. Download and install Thunderbird application.
  2. Enter your name and Kerio Connect mail address.
  3. Choose IMAP as the connection type.
  4. Enter the server details, test the connection, and start Thunderbird.
  5. Go to Hamburger Menu (three lines) >> Themes & Extensions and add ImportExport NG Tool.
  6. Right-Click on Local folders >> Import Export NG Tools.
  7. Import MBOX >> Import MBOX from directory.
  8. Open the MBOX files in the Thunderbird local folder.
  9. Right-click on the imported MBOX >> Choose Move To or Copy To.
  10. Select the Kerio Connect Mailbox as the destination to import MBOX.

Note: Even if you access your account via Kerio webmail, you will be able to open MBOX emails there.

Method 2: Server Admin Level MBOX to Kerio Import

Server admin can bulk import MBOX in the Kerio mailbox without any external application on the server device only.

Tip: Before you start, always back up the Kerio user account.

Pre-Requisite: Convert MBOX Files into Maildir format, as the Kerio server stores emails in Maildir format, not MBOX.

  1. Copy the MBOX data in a Kerio-supported format.
  2. On the server machine, locate the Kerio Mail Store.
  3. On Windows: C:\Program Files\Kerio\MailServer\store\
  4. On Linux: /opt/kerio/mailserver/store/
  5. Open Mail >> your Domain >> User Mailbox in which you need to import MBOX data.
  6. Paste the data in the Maildir folder.

You can now access your Kerio mailbox via Webmail, Outlook, or Thunderbird to view newly imported MBOX emails.

Enterprise-Level Solution to Import MBOX to Kerio Mailbox

BitRecover MBOX Converter for Kerio account is a secure software solution to directly transfer multiple large MBOX files from any source into a Kerio webmail account with all its email attributes fully preserved. Widely trusted by businesses & IT admins for MBOX to Kerio migration. Download the free trial today.

  • No MBOX to Kerio server import restrictions
  • Support direct MBOX transfer for user & admin accounts with secured connection
  • Lets you convert MBOX data into Kerio-supported format for server-level imports.
  • Preserves email folder structure, attachments, email metadata, and headers.
  • Advanced filter for selective MBOX email to Kerio import based on date, to, from, and subject keyword.

How to Use the MBOX to Kerio Mailbox Converter Tool?

  1. Download the tool to import MBOX to the Kerio server.
    MBOX to Kerio Converter Tool
  2. Select MBOX files or folders.
    Add MBOX files or folder to be importer in kerio server account
  3. Open, preview, and select the folder in MBOX data files to be imported into the Kerio mail account.
  4. Choose IMAP as the saving option for the Kerio account.
    saving Option for MBOX to Kerio conversion
  5. Enter the credentials, Kerio Mail ID, password, IMAP host name, and Port Number (Contact admin or find it in webmail configuration).
  6. Press Convert to start the MBOX to Kerio Server Mailbox migration.

Comparison: Which is the Best Way to Add MBOX to Kerio Connect?

Feature Thunderbird Method Server Admin Method BitRecover Tool
Bulk Data Handling Not suitable (4GB limit and depends on local storage) Possible but complex Designed for bulk data
Data Loss & Corruption Attachment and folder structure loss High manual handling risk Automated low-risk process
Who Can Perform User or Admin (with credentials) Server Admin only User and Admin
Downtime Slow (depends on the internet and sync) Medium (depends on server and process) Fast
Additional Features No features No features (CLI/manual process) Filters, Preview, Log Report

Need Help Importing MBOX to Kerio Mailbox?

Get in touch with BitRecover Experts via live chat for any queries or to request more features to meet your MBOX to Kerio Server migration needs.


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