PST to Mimecast Case StudyManpower:
getting ownership right.

Organisation

Manpower (UK)

Sector

Recruitment

Source

PST files across the network

Destination

Mimecast archive

Scale

16 TB · 300+ UK locations

Result

Fully automated from source to destination

The situation

Manpower, one of the world's largest recruitment companies, was centralising messaging for its UK operation and had chosen Mimecast for perimeter protection and as a historical email repository. Years of mail sat in PST files spread across more than 300 locations: 16 TB in all.

The pilot that changed the plan

A manual ingestion trial was run for ten users. Two of them were siblings, and after ingestion each found the other's email in their archive. Nobody was hurt, but the point was made. If ownership is wrong for two related employees in a ten-person pilot, what happens at the scale of a whole business, where the wrong pair might be a director and someone with a grievance? Ownership had to be determined reliably, by evidence, and automatically.

How the project ran

1. Find every PST. The network was crawled across all locations to locate PST files.
2. Analyse close to the data. A distributed architecture did the heavy analysis locally, keeping traffic off slow WAN links to branch offices.
3. Collect ownership evidence. For each file, the platform gathered the senders and recipients of the messages inside it, the file-system owner and the profile folder path.
4. Decide by rule. User-definable rules and confidence thresholds turned that evidence into an owner for each file.
5. Prepare and send. Files were renamed to avoid collisions, cleared of corrupt messages, compressed, and delivered directly to Mimecast on a schedule.
6. Tidy up. Once a PST was safely ingested, the original could be removed from the network automatically.

Results

• 16 TB of PST data from 300+ UK locations prepared and delivered to Mimecast
• Ownership assigned from evidence and rules, not by hand
• Corrupt messages removed before ingestion
• A fully automated process from source to destination, including clean-up

What this means for your project

Every PST project has the same hidden risk: putting someone's email in someone else's mailbox. It's a data breach created by the project meant to reduce risk. Ownership has to rest on evidence from inside the file as well as where it's stored, with rules you can explain to an auditor. That applies whether the destination is Mimecast, Microsoft 365 or Exchange.

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