Case Study: Convert 3.2 TB Accessible of IBM Notes NSF files into Outlook PST Format
By katherine 17-07-2026 16
About the Case Study
A multinational engineering consultancy with offices in India, UAE and Singapore decided to retire its IBM Notes environment after more than a decade. The company had plans to standardize communication on Microsoft Outlook and Microsoft 365, to ease collaboration and reduce infrastructure costs.
Over the years the organization had amassed thousands of IBM Notes NSF files, with client contracts, engineering drawings, project discussions, approvals, meeting schedules, contacts and archived correspondence. Since a lot of this information was still needed for active projects and for compliance audits, maintaining mailbox integrity during migration became a major concern.
The IT department started experimenting with manual migration methods. But after several unsuccessful pilot migrations, they used DataVare NSF to PST Converter to complete the migration efficiently and without losing any mailbox data.
Sector
Engineering & Infrastructure Consulting Company Stats
Parameter | Value |
|---|---|
Employees | 480 |
IBM Notes Mailboxes | 452 |
Total NSF Data | 3.2 Tb |
Total E-mails | 7.8 M |
Attachments | 980,000 |
Contacts | 61.5K |
Calendar entries | 205K |
Migration Period | 14.5 hr |
Data Loss | 0% |
Business Problems
Before the migration could begin, the IT department had to:
- Convert hundreds of IBM Notes NSF files to Outlook PST format.
- Maintain the original folder hierarchy in the mailbox.
- Keep email properties and metadata.
- Transfer contacts and calendar items.
- Do not extract attachments from their emails.
- Minimize project downtime.
- Complete migration during the planned maintenance window.
- Make sure users can immediately access historic emails in Outlook.
Understanding file formats
NSF
NSF (Notes Storage Facility) is the main database format used by IBM Notes (formerly Lotus Notes). It stores email, contacts, calendars, journals, tasks and other mail box information.
Why convert NSF to PST?
If your organization is transitioning from IBM Notes to Microsoft Outlook, you will require your mailbox data in PST format, as Outlook cannot read NSF files natively. Employees are allowed to access their old emails by converting NSF to PST without the need to manually rebuild mailboxes.
Evaluation of Migration Methods
Manually Migrate
First, the IT department looked at the manual migration methods available through IBM Notes and Microsoft Outlook.
Manual Procedure
- Set up IBM Notes.
- Set up Microsoft Outlook.
- Export Mailbox Data.
- Import mailbox to Outlook.
- Repeat the process for each employee.
- Check imported mailbox content.
Result of the manual migration
The manual method worked for a few small mailboxes but as mailbox sizes grew it became more and more difficult. The migration was a constant process of supervision, a lot of checkpoints and a lot of administrator involvement.
Challenges encountered
- Time-consuming process
- One mailbox at a time
- Requires IBM Notes and Outlook
- Administrative burden
- Greater chance of incomplete migration
- Not ideal for enterprise-level projects
Moving one mailbox manually is no problem. Automation needed for migration of hundreds.
Migration Using Software
To make the project easier, the IT department chose DataVare NSF to PST Converter.
The application converted mailbox data to Outlook PST format after selecting the NSF files, retaining emails, folders, contacts, calendars, attachments and email properties. The converted PST files were then imported into Microsoft Outlook for the employees to use.
Migration Result
The migration completed successfully without mailbox corruption.
Project Outputs
- Migrated all 452 NSF mailboxes successfully
- Original folder hierarchy is maintained.
- Keeps sender, recipient, subject, timestamps and other email properties.
- Migration of contacts and calendar items.
- Retained attachments with the original email they were attached to.
- Less manual administrative work.
- Completed migration ahead of planned deadline.
- Employees could work immediately after the migration.
Benefits of the solution
- Bulk NSF conversion: Converts multiple IBM Notes mailboxes in a single project.
- Maintain Folder Structure: Keep the current mailbox organization.
- Complete Metadata Preservation: Keeps sender, recipient, subject, timestamps and email status.
- Attachment Security: Transfers attachments along with their corresponding emails.
- Easy-to-use Interface: For IT administrators and business users.
- Shorter migration time: Automates repetitive works. Reduces manual work.
- Business Continuity: Employees get access to historical communication right after migration.
Practical Considerations
IBM Notes Ecosystem
You need to have the NSF source files available when you start the migration.
Availability of Storage
Make sure you have enough disk space for the converted PST files.
Post-Migration Validation
Review some of the migrated mailboxes before they are made available to employees.
Migration Process
- Install the NSF to PST Converter.
- Open the application.
- Choose NSF files to browse.
- View the mailbox contents.
- Choose PST as the output format
- Go to the destination folder.
- Begin the conversion.
- Track migration progress.
- Import PST files in Outlook.
- Validate mailbox data.
Best practices for migration
- Make a backup of NSF files before migration.
- Initially, test the migration with a small sample mailbox.
- Ensure Outlook compatibility.
- Provide enough storage space for PST files.
- Review of converted mailboxes before rollout.
- Keep original NSF files until verification is done.
- Keep records of mailbox ownership up to date and accurate.
Recommended For
Enterprise (Large)
Switching from IBM Notes to Microsoft Outlook.
Corporate IT Teams
Bulk mailbox migrations
Government Organizations:
Modernize legacy e-mail infrastructure
Legal and Financial Firms
Maintaining compliance records and archiving communications.
Educational establishments
Moving faculty and admin mailboxes.
Frequently Asked Questions
Why to convert NSF to PST?
This gives Microsoft Outlook access to the data of IBM Notes mailbox.
Will the folder hierarchy remain the same?
Yes. Maintains original folder structure.
Are attachments relocated?
Yes. Attachments are still associated with their emails.
Do you keep the email metadata?
Yes, sender, recipient, subject, timestamps, other properties are preserved.
Is it possible to convert several NSF files at once?
Yes. The software supports batch conversion.
Do I need to back up NSF files before migration?
Yes. It is always recommended to take backup before any migration project.
Conclusion
This case study illustrates that migrating hundreds of IBM Notes mailboxes manually is a challenging and time-consuming task to manage in an enterprise environment. With the help of NSF to PST Converter, the organization was able to migrate 3.2 TB of mailbox data preserving emails, attachments, contacts, calendars, folder hierarchy and metadata. The automated process saved administrative time, minimized migration downtime, and allowed employees to continue working without interruption post switch to Microsoft Outlook.
