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

Dovecot is the leading IMAP server for UNIX/Linux systems. It is free, and open-source, with security as its primary focus. However, in recent times industry giants like Microsoft have closed the gap and provided a host of other facilities (Teams, Onedrive, SharePoint, etc) that push users to Migrate Dovecot to an 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 what are the reasons behind the migration and what are the pre-migration steps.

What are the Reasons for Dovecot to Office 365

The idea behind Dovecot is great, but it misses the mark on many levels. As your business grows and develops, mail servers like Dovecot may seem too easy. Its Linux-based environment may be too complicated for many who don’t have a lot of technical knowledge and prefer to move to a more user-friendly platform like Office 365.

• Office 365 offers strong security and server reliability. This means you don’t have to worry about manual maintenance. If you’re a business looking to automate your workflow, Office 365 is the way to go.
• Microsoft 365 also allows you to add domains from third-party hosts and send emails directly to your Outlook and Outlook for Work (OWA) accounts.
• Office applications like Word, Excel, and PowerPoint are integrated into Office 365 and included in the license at the same price.
• You don’t need to use any technical commands to get things done on Office 365, and you can easily link and integrate your G Suite, Dropbox, and other cloud services with Office 365.
• Calendar, contacts, email, and many other applications like SharePoint, Teams, and Yammer are accessible through Microsoft’s user interface.

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 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.

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 sequentially 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.

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 imap.domain.com -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

Conclusion

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.