Technical Tutorial to Migrate Dovecot to Office 365 (Microsoft 365) 

Migrate Dovecot to Office 365 in a Simple Manner

Published By Aldrich Calvin
Anuraag Singh
Approved By Anuraag Singh
Published On August 16th, 2023
Reading Time 7 Minutes Reading
Category Migration, Office 365

Dovecot is the leading IMAP server for UNIX/Linux systems. It is free, open-source, with security as its primary focus. However, in recent times industry giants like Microsoft have closed the gap and provide a host of other facilities (Teams, Onedrive, SharePoint, etc) that push users to Migrate Dovecot to Office 365 environment. Moreover by undertaking this data transfer users can free themselves from the complicated command-line Linux machines and instead use a Windows GUI. Therefore, let’s begin by addressing the pre-migration steps.

Prerequisites for A Successful Dovecot to Office 365 Migration

Given below is a list of the steps that need to be done before the actual migration can start. Do not overlook these settings as this may cause the migration to fail.

  • First of all, if you have a unique third-party domain name for your IMAP business, attach it to your Microsoft 365 account as an accepted domain.
  • Once the domain verification is complete, add users to Office 365 service this is to provide an endpoint for the data.
  • Now create a migration CSV file, the Dovecot IMAP server uses a Simple Authentication and Security Layer (SASL), so use the format User_UserName*Admin_UserName. 
  • Raise the number of connections for your IMAP server. Moreover, it acts as a safety net, in case one connection breaks abruptly, others can still continue the Dovecot to Office 365 migration at a reduced speed.
  • Obtain the FQDN of the IMAP server and configure the firewall to allow IMAP connections. 
  • Enable ‌admin account-level permissions to access all mailboxes present within the IMAP server. 
  • Log in to EAC and bring the Exchange Online PowerShell commands into your local Windows PowerShell session if you intend to use them.

Read More: The Complete Guide to Migrate MDaemon to Office 365 Account Easily

There are two manual methods for completing an IMAP migration, which we will discuss in more detail in the coming sections.

Basic Manual Method to Migrate Dovecot to Office 365

Follow the steps in a sequential manner for the best results.

  • Launch the EAC (Exchange Admin Center)
  • Visit the “Migration” section and hit the “Add migration batch” button.
  • When the Add migration page opens find the area to type in a unique name. Example: “Test-Dovecot-Office”.
  • From the dropdown list choose “Migrate to Exchange Online”, then pick the path for mailbox migration, and proceed by hitting “Next”.
  • Look at all the prerequisites on the “Prerequisites for IMAP migration page”. Check for any issues and resolve them, then click Next to move ahead.
  • Add a destination for the data via the “Set a migration endpoint” page. Use proper naming convention but don’t make any changes in any other options, hit ”Next”.
  • Now, on the IMAP migration configuration page enter the name of the source server and leave the other options as they are.
  • If a message saying “new endpoint created” appears it is safe to press “Next”.
  • It’s time to attach the CSV file of user mailbox data. Browse for it from the options provided in the interface add it and press “Next”.
  • Don’t make any changes in the “Select configuration settings” page simply hit the “Next” button and proceed to migrate Dovecot to Office 365.
  • On the “Schedule batch migration” page set both the start and end points for the migration batch, Save the setting, wait for verification, then press “Done”.
  • Verify the status in the “Batch” option of the “Migration” section of the main menu of EAC also ask the users to log in and check for any disruptions.
  • Update the MX record to point towards the new destination and remove it from the original server as well.
  • Finally, delete the migration batch.

Source: Migrate other types of IMAP mailboxes to Microsoft 365 or Office 365

Powershell Commands for Dovecot to Office 365 Migration

Step 1. Make and verify a new Powershell connection:

Code: Test-MigrationServerAvailability -IMAP -RemoteServer <FQDN of Dovecot IMAP server> -Port <143 or 993> -Security <None, Ssl, or Tls>

Step 2. Create an endpoint for the migration.

Code: New-MigrationEndpoint -IMAP -Name IMAPDovecotEndpoint -RemoteServer -Port 993 -Security Ssl

Step 3. Verify the endpoint connection.

Code: Get-MigrationEndpoint IMAPDovecotEndpoint | Format-List EndpointType,RemoteServer,Port,Security,Max*

Step 4. Initiate an IMAP batch migration process by attaching the CSV file.

Code: New-MigrationBatch -Name IMAPDovecotBatch1 -SourceEndpoint IMAPEndpoint -CSVData ([System.IO.File]::ReadAllBytes("C:\Users\Administrator\Desktop\IMAPDovecotmigration_1.csv")) -AutoStart

Step 5. Check the status of Dovecot to Office 365 migration with the help of the following command:

Code: Get-MigrationBatch -Identity IMAPDovecotBatch1 | Format-List Status

Step 6. Make changes to the MX record on your domain provider’s website. Edit the following parameters.

Record Type: MX
Priority: Maximize its value (lower the number higher the value), usually set at 0.
Host Name: @hostdomain
Points to address: Get the value from the admin center and put it here.
TTL: 3600

Step 7. End the Migration Batch request to avoid data duplicity:

Code: Remove-MigrationBatch -Identity IMAPDovecotBatch1

Source: Use PowerShell to perform an IMAP migration to Microsoft 365

To avoid the hardships of manual techniques we have an automated tool at your disposal.

Migrate Dovecot to Office 365 Professionally

Out of the many such tools available in the market, SysTools IMAP to Office Migrator stands apart. It is due to the fact that it is designed with a philosophy to ease up  Dovecot to Office 365 migration as much as possible. Moreover, to achieve this aim the utility combines advanced algorithms with a simplistic UI to move data from one point to another. 

Additionally, the “user first” policy is incorporated into its design, meaning it has multiple features which users can utilize before, during, and after migration. Follow the steps below to use the tool.

Step 1. Get the tool and launch it, pick the IMAP server option as the origin and Office 365 as the destination.

Open Tool

Step 2. Go to the Workload area and tick the box beside emails, then add a Date filter if required.

Add Date Filter

Step 3. In the left side menu, head to the Source section and pick Other from the IMAP server field; then, provide the necessary information in the given space.

Validate Source

Step 4. Validate the Admin email address and the Application ID once done press “Next”

Validate Destination

Step 5. You have the option of either uploading the user’s data right away or downloading the template first and customizing it before uploading the user data.

Attach Users

Step 6. Finally, verify the users from the preview window and select all the ones whose data needs to be transferred. Validate and hit Start migration to begin the process.

Start migration

We will now look at some of the qualities that have earned this tool the admiration of all users.

Features of the Utility

This tool is the best choice for Dovecot to Office migration due to its many advantageous features such as.

  • Send up to 20 users’ data in bulk at a time.
  • The tool maintains the entire folder structure as it is.
  • With this tool, you can get detailed reports of the migration.
  • It helps you to move all mailboxes with zero data loss.
  • Make use of the Date filter option to pick out and transfer specific folders. 

Also Read: How to Migrate IceWarp to Office 365 and Shift Your Email Data


In this discussion on how to migrate Dovecot to Office 365, we presented multiple solutions like the default method and Powershell commands. Apart from this the steps to use a professional utility are also present here. Moreover, with the tool users can easily overcome the challenges posed by ‌manual methods.