How a Global Reinsurance Company Automated a 100TB Email Archive Migration with Transvault

insurance-umbrella

A leading global reinsurance company undertook a significant digital transformation initiative to migrate its email archive from an on-premises eDiscovery platform (OpenText Recommind with Hitachi Content Vault storage) to Microsoft 365.

This involved migrating over 100TB of data, including email archives spanning legal hold data and compliance-sensitive content. Given the scale and complexity, the organisation required an automated, efficient, and auditable migration process. By leveraging Transvault Migrator, the company successfully automated the critical import steps, ensuring a smooth, accurate, and compliant transition to Exchange Online.

Source
OpenText
Target
Microsoft 365
Data Size
100TBs
Solution
Transvault Migrator

The Challenge

The company’s legacy eDiscovery platform was not natively supported by Transvault Migrator, necessitating a custom migration approach. Key challenges included:

  • Massive Data Volume: Over 100TB of archived emails requiring migration to Microsoft 365.
  • Legal & Compliance Requirements: Data older than 7 years was excluded unless under legal hold, while active and inactive user data required special handling.
  • Infrastructure Constraints: Migration needed to avoid disrupting ongoing eDiscovery processes.
  • Automating Complex Import Steps: Transvault Migrator needed to integrate seamlessly with the organisation’s workflow to minimise manual intervention.

The Solution

The reinsurance company and Transvault collaborated to develop a highly automated migration workflow, addressing the challenges with the following key features:

1. Data Extraction & Preparation

  • Extracted email archives into PST files, the preferred format for Transvault Migrator.
  • Organised PST files using unique custodian identifiers for accurate tracking.
  • Applied filtering rules: Migrated only data newer than 7 years unless flagged for legal hold.
  • Developed a rolling system for inactive users: Create mailbox → Migrate → Convert to inactive mailbox.

2. Automating Import Readiness

  • Configured daily automated gathering in Transvault Migrator to register source files in the ESSMIG_MAILBOX table.
  • Developed a fallback mechanism: Manually triggered the gathering process when necessary.
  • Integrated validation checks into the migration workflow to ensure proper data registration before proceeding.

3. Seamless Mailbox Mapping & Import Handling

  • Updated Transvault database directly to map email archives to the correct Exchange Online mailboxes.
  • Defined two import queues based on data size:
    • Primary mailbox queue (active users)
    • Archive mailbox queue (larger datasets)
  • Utilised Transvault’s PowerShell module to trigger automated imports.
  • Continuous monitoring via Transvault database queries:
    • Queue status checks
    • Migration progress tracking

4. Error Handling & Compliance Auditing

  • Implemented automated retry logic:
    • Up to 3 retries for failed mailboxes before manual intervention.
    • Special handling for Exchange Online quota errors – postponed retries for a week.
  • Ensured full auditability by correlating Transvault logs with legacy system export logs.
  • Maintained compliance oversight by identifying and isolating items too large or incorrectly formatted for Exchange Online.

Results & Benefits

  • Successfully migrated 100TB of data while meeting compliance and legal hold requirements.
  • Automation reduced manual workload, allowing the IT team to focus on high-priority tasks.
  • Seamless integration with the organisation’s existing infrastructure ensured business continuity during migration.
  • Robust auditing capabilities provided complete traceability of migrated data.

This ambitious archive migration demonstrates the power of automation, scalability, and compliance-driven strategies. By leveraging Transvault Migrator and integrating it into a structured migration workflow, the reinsurance company achieved a seamless, efficient, and legally compliant transition to Microsoft 365.

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Relevant resources

Planning an Email Archive Migration

Email archiving is best practice in many industries, but if you’re working in a heavily regulated sector like financial services, healthcare, energy, life sciences, education or government, it’s essential. 

Whether you’re migrating your email archives to consolidate, centralise or provide greater security for your data, it’s important to plan properly to ensure the transfer is thorough and secure. Otherwise, you risk data loss, failure to comply with regulatory requirements and issues for end-users.

Posted by Liam Neate on Apr 07, 2025 Last updated Apr 11, 2025

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