GainTools OST to PST Converter is the best and most powerful OST file recovery and conversion tool for users who need to recover inaccessible or corrupted OST data and convert it into a usable Outlook PST file. It offers mailbox preview, selective folder export and support for emails, contacts, calendars, notes and tasks. The option to check recoverable data before conversion makes the process more convenient, especially when working with a problematic OST file. Overall, it is a practical choice for OST recovery and mailbox migration.

You can convert multiple EML files into a single PST using a standalone tool like TrustVare EML to PST Converter. For a few EML file conversions, you can use the manual method, but it becomes hard and time-consuming when you have large files, so it does not guarantee accurate migration. So my preferred choice is to use a reliable utility like this. This software supports features like bulk processing, preview option, selective conversion, and accurate conversion. I also used this tool for email to PST export; it preserved all information accurately.

For a free way to import PST files to Office 365, Microsoft’s native PST Import is the first option that you can try; this manual way works well when you only have a few PST files.

The problem comes with the manual method. You need Microsoft 365 admin permissions, upload the PST files to Microsoft’s import location, prepare the CSV mapping that tells Microsoft which PST goes to which mailbox, and then create the import job. For a few files that is manageable, but with dozens of PSTs it becomes repetitive and easy to mis-map a mailbox.

When I had to move several old PST archives into Microsoft 365, I wanted a simpler way to review the data before importing it. I ended up checking TrustVare PST to Office 365 Converter because it could read the PST directly, preview the mailbox, let me select the required folders, and transfer the selected data to Office 365. That was useful when I didn’t want to import an entire archive blindly.

So, for a couple of PST files, Microsoft’s free import route is enough. For multiple archives or selective PST migration, a direct PST to Microsoft 365 tool can save a lot of the manual handling.

You can convert MBOX files to PST format using a specialized converter tool that is built to easily migrate MBOX data into Outlook-compatible PST format. Because there is no direct method to migrate MBOX files to PST format, using a third-party utility becomes a reliable option. In that situation, GainTools MBOX to PST Converter is an expert solution for accurate conversion. It supports bulk processing with a preview feature and selective data transfer and ensures complete data safety during MBOX file export.

To migrate Lotus Notes to Office 365 without losing emails, I’d use a direct NSF migration instead of manually moving emails. Manual transfer can become difficult when the NSF file contains many folders, attachments, and other mailbox data.

I’d consider Softaken Lotus Notes to Office 365 Migration Tool for this situation because it lets me add the NSF file, preview the mailbox, select required folders and transfer the data to Microsoft 365. It also supports emails, attachments, calendars, notes, journals, and folder structure.

Easy Migration Steps:

• Add NSF: Select the Lotus Notes database.
• Preview Data: Check the available folders and mailbox items.
• Select Content: Choose the required data.
• Connect Office 365: Enter the destination account details.
• Start Migration: Transfer the selected data.
• Verify Mailbox: Check emails, attachments, and folders in Office 365.

For a larger migration, I’d test one NSF database first before moving the rest.

To move emails between IMAP servers without losing important data, use an IMAP migration tool for large or multiple mailboxes. For a small mailbox, you can manually add both IMAP accounts to an email client and copy the folders, but this becomes difficult to manage at scale.

For safe IMAP migration, you can trust some tools like DataVare Mail Migration Tool that can move emails from one IMAP account to another while keeping attachments and the existing folder structure. It also lets you select specific mailboxes or filter emails when you don't want to transfer everything.

Before starting the full migration, test one mailbox and compare the folders, email count, and attachments on the destination server. This helps catch login, folder-mapping, or synchronization issues before they affect the complete migration.

In 2026, moving an IMAP mailbox to Microsoft 365 has become much easier, but the overall experience depends on the method you choose. If you're migrating a single mailbox, the manual method may be enough. For multiple mailboxes or business accounts, an automated approach usually saves time and requires less effort.

Method 1: Manual IMAP Migration
If you want to use Microsoft's built-in migration process, follow these steps:

• Sign in to the Microsoft 365 Admin Center.
• Create the destination mailboxes if they don't already exist.
• Enable IMAP access on the source email account.
• Open the Exchange Admin Center and create a new IMAP migration batch.
• Enter the IMAP server details and mailbox credentials.
• Start the migration.
• After it finishes, verify the emails, folders, and attachments.

Limitations of the Manual IMAP to Microsoft 365 Migration Method:

• It takes a lot of time when you have multiple mailboxes to migrate.
• A small configuration mistake can force you to restart the migration from the beginning.
• Finding and fixing migration errors can be difficult for non-technical users.
• After the migration, you still need to check that all emails, folders, and attachments have been transferred correctly.

Method 2: Automated IMAP to Microsoft 365 Migration
When I had to move multiple IMAP mailboxes to Microsoft 365, I chose WholeClear IMAP to Office 365 Converter because I wanted a simpler way to migrate several accounts without spending time configuring migration batches.

The process was straightforward:

• Launch the application.
• Enter the IMAP account credentials.
• Sign in with the Microsoft 365 account.
• Select the mailbox you want to migrate.
• Start the migration process.
• Once it finishes, verify the mailbox folders, email count, and attachments.

What I liked was that I didn't have to export mailbox files or migrate every account separately. The emails, attachments, folder hierarchy, and other mailbox details remained intact after the migration, which made the move to Microsoft 365 much easier to manage.

If your goal is to migrate Google Workspace to an IMAP server in bulk, use a migration method that supports multiple mailboxes instead of moving one account at a time. It saves time and makes the migration much easier to manage, especially for business or organizational accounts.

I recently migrated several Google Workspace mailboxes to a new IMAP email server using a trusted utility instead of doing it manually because the manual method was not practical for the large G Suite to IMAP conversion, plus it is also time consuming to handle bulk data.

For the bulk migration, I used Softaken IMAP to IMAP Migration Tool because it directly transfers mailboxes without downloading or exporting each account separately. I selected the required user accounts, connected both the Google Workspace and destination IMAP servers and migrated them in batches.

A few things I'd recommend before starting:

• Enable IMAP in every Google Workspace account.
• Verify the login credentials for both servers.
• Test the migration with a small batch first.
• Compare the mailbox folders, email count, and attachments after each batch.
• Keep the Google Workspace accounts active until the migration is fully verified.

The above approach made my task simple, allowing me to perform bulk Google Workspace to IMAP migrations effectively.

If you need to manage a large Outlook mailbox more efficiently, splitting the PST file is often the reason many users look for a better solution. Keeping years of emails in a single PST can make the mailbox harder to organize, so dividing it into smaller files by size, year or folder makes everyday management much more convenient.

Instead of separating Outlook data manually, I'd suggest having a look at WholeClear Split PST Software. It's an offline utility that offers different splitting options, allowing you to create smaller PST files based on the way you want to organize your mailbox. Since it supports both ANSI and Unicode PST files, it can be used with PST files created in different Outlook versions as well.
If your Outlook data file has become difficult to handle, trying the free trial first is a practical way to check whether it suits your mailbox management needs.

When Windows Live Mail displays identical messages more than once, the duplicates are usually the result of repeated imports, restored backups or multiple mailbox exports. You can delete them manually for a few messages, but it gets hard when you get hundreds of email with similar subjects and attachments.

A more practical approach is to clean the exported EML files before reorganizing the mailbox. I would suggest GainTools EML Duplicate Remover, as this trusted offline tool works with Windows Live Mail EML files without requiring the email client to be installed. It compares the actual email details instead of relying only on filenames and helps remove duplicate messages while preserving genuine emails and attachments.

I hope this points you in the right direction.