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The migration from IMAP to Office 365 represents a prevalent undertaking for organizations as they transition to cloud-based solutions. Nonetheless, this migration process can be intricate, with administrators encountering numerous challenges when transferring their IMAP mailboxes to Office 365. If you find yourself grappling with similar issues during your data migration, it’s imperative to address and troubleshoot these errors proactively.
In this article, we will talk about the most common errors faced by administrators while migrating their IMAP mailboxes to Office 365, along with some effective troubleshooting options.
Types of Issues with IMAP Migration
Generally, there are two types of issues that administrator faces while migrating IMAP mailboxes to Office 365. The most common problem is related to the IMAP migration batch – either it gets started with issues or doesn’t start at all. The other issue is the migration speed, which usually happens due to a large mailbox or slow network connection.
Migration Batch Issues on Starting
After successfully creating a migration batch, you may encounter several issues during the IMAP to Office 365 migration. In this discussion, we’ll explore the common challenges that can arise throughout the process.
- Duplicate Emails
Many users frequently encounter the issue of duplicated emails within their IMAP mailboxes. This problem typically arises during the migration process when the IMAP folder is inadvertently omitted from the “Exclude folder” settings. Fortunately, you can effectively address this issue by employing the following solutions:
- Select the IMAP folder in the Exclude folder section during the migration batch creation
- Eliminate labels from IMAP emails. Select the specific emails with labels by filtering them, clear the selected checkboxes against all labels, and click Apply
- The Mailbox is Full
This error arises when your Office 365 mailbox storage reaches its limit, typically as a result of the accumulation of duplicate emails. To rectify this issue, it’s essential to free up space within your Office 365 mailbox. You can achieve this by either eliminating duplicate items or by following the method outlined above to create a migration batch while removing associated labels.
It is crucial to emphasize the importance of removing labels from your emails before initiating the data migration process. Furthermore, when migrating data to the cloud, it’s advisable to exclude the Gmail folder to streamline the process.
- Trouble When Signing In to the Account
When you initiate the migration batch, you might encounter a message that reads, “We’ve encountered an issue while trying to sign in to this account. Please double-check the accuracy of your username and password.” This error typically appears when using a CSV file for data migration, and the problem arises from incorrect credentials within that file.
To resolve this issue, it’s crucial to ensure the CSV file contains accurate and valid credentials, or you can use administrative credentials with the necessary access privileges. If you are confident that the provided details are correct, it’s advisable to confirm the existence of the IMAP mailbox. You can do this by navigating to the “recipients > mailboxes” section in the Exchange admin center.
When Migration Batch doesn’t Start Properly
When confronted with problems during IMAP to Office 365 migration, especially in cases where the migration batch fails to start, it is crucial to apply a variety of troubleshooting solutions.
- Batch (name) Already Exists
This common error arises when you attempt to use an identical name for a migration batch already in existence. To rectify this situation, you have two options: either create a new migration batch with a distinct name or remove the current migration batch by navigating to ‘recipients’ > ‘migration’ in the Exchange Admin Center (EAC), selecting the existing batch, and clicking the ‘Delete’ button. Afterward, you can proceed by creating a fresh migration batch with the desired name and continue with the IMAP to Office 365 migration process.
- Errors with the CSV Files
Often, when you use a CSV file to migrate IMAP mailboxes to Office 365, it displays multiple errors when the migration doesn’t start. Some common errors that you can troubleshoot:
- CSV file contains more than 50,000 Users
A CSV file can only contain a maximum of 50,000 users at one time. So, if you’re using a CSV file to migrate IMAP mailboxes, make sure it has less than 50,000 user credentials.
- The uploaded file can’t be empty
Make sure the CSV file is not empty when you’re creating a migration batch.
- Column is missing from the CSV file
This error occurs when essential columns, such as email address, username, or password, are absent in the CSV file. To address this issue, ensure that the mandatory columns are present in the first row of the CSV file, and then proceed to resubmit the file.
Connection to the Server is Not Completed
This error represents a common challenge encountered during the IMAP to Office 365 migration process, characterized by complications arising from the specification of the IMAP server’s Fully Qualified Domain Name (FQDN) across diverse scenarios. To effectively troubleshoot connectivity-related issues, please follow the steps outlined below:
When creating the migration batch with no endpoints, you can follow the below steps to specify the public FQDN correctly.
- Go to the Exchange Admin Center and log in with administrator credentials
- Now, click Recipients and select Migration
- Click the ‘+’ icon and select the Migrate to Exchange Online option
- Select IMAP Migration and click Next
- Now, click the Choose file option, browse, and add the CSV file, and click next
- After that, enter the public and resolvable FQDN and click Next to create and run the migration batch.
While creating the migration batch with existing endpoints, follow the below steps to determine the public FQDN.
- Go to EAC and click Recipients >> Migration
- Now, click More Options to select the Migration endpoints
- Check the FQDN for the IMAP Server and recreate the migration endpoint if it is inaccurate or not publicly resolvable
Mailbox Migration is Running Too Slow
If the IMAP to Office 365 migration is too slow, you can follow the below points to deal with various situations.
- Go to EAC and login with administrator credentials
- Navigate to Recipients and select Migration, and then select the Migration endpoints
Double-click on the IMAP migration endpoint, and put the value greater than 20 in the Maximum concurrent migration
Some other troubleshooting methods you can try to improve your migration speed include:
- Verify the migration report by going to the View details section of the migration batch. It will display whether the items are synching or not
- Improve the connection limits to the IMAP server. Most IMAP servers have per-user limits, per-IP address limits, and overall connection limits. So, make sure your server is configured to allow the optimal number of connections.
- Check the IDS settings and server settings to improve connection
- Try deleting the existing migration batch and recreate the batch to enhance the connection
Moreover, you can also utilize the Office 365 Network Analysis Tool to help analyze networking-related issues between the Office 365 services and external networks.
If the troubleshooting methods mentioned above are not yielding the desired results for your IMAP mailbox migration to Office 365, it’s a clear sign that the current migration approach is less than ideal. Furthermore, manual migration processes may not always be the best fit for transferring IMAP mailboxes to Office 365.
To streamline your migration and ensure a smooth transition, it is highly recommended to leverage an automated solution such as the Kernel IMAP to Office 365 tool. This advanced utility is specifically designed to facilitate IMAP mailbox migration to Office 365, offering a wide array of intelligent features and functionalities to simplify the process. What’s more, its user-friendly integrated graphical user interface (GUI) caters to both technical and non-technical users, making the migration process accessible and efficient for everyone.
IMAP to Office 365 migration is one of the most common migrations organizations perform when deciding to move to the cloud. But, using the manual methods can bring a lot of errors during, before, and after the migration. So, it is advisable to use an automated solution to migrate your IMAP mailboxes. In this article, we discussed how you could troubleshoot IMAP to Office 365 migration errors with practical solutions and improve the migration speed manually.