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Migration to (and from) Mimecast…..over a nice Cup of Tea and Biscuit

There’s a lot to think about when migrating email archives.  We caught up with Migration Consultant Jim Fussell over a cup of tea and a biscuit to pick his brains on getting your data into (and out of) Mimecast..

So James, what’s the first step?  Well, first you’ll need to define what you’re migrating. Often this will simply be a case of selecting messages within a time-frame that matches your retention policy. Lots of customers decide to migrate literally everything up until the point that their Mimecast Journal Capture service kicked in (or stopped).

Of course you might want to filter what you’re migrating, or exclude email from leaver’s mailboxes.  It’s up to the customer, their email retention policies any legislation that applies to their industry.

Can you migrate directly into Mimecast?

No, currently you will provide your data in PSTs or EML files. The PSTs need to be structured and named in line with Mimecast’s requirements, which we sort out.  We also keep them below a certain size to avoid corruption. Mimecast sends an encrypted storage device which they pick up when you’re ready and take it from there. Transferring data using this method is actually faster for the larger sites we deal with as network bandwidth can be a bottleneck.

Any other top tips for handling the PSTs in transit?  Yes. We always recommend customers store a copy of extracted PSTs until they receive confirmation that the ingestion is complete, and although it’s temporary, make sure it’s backed up.  It’s also worth bearing in mind that archives like Enterprise Vault compress and de-duplicate your email, so when you extract to PSTs you’ll need storage space that is 2 or 3 times bigger than your archive.

How long will it take? Hmmm, this is the million dollar question.  We get asked this a lot and the answer is, “It depends”.  We automate the extraction process making it a lot quicker than doing it manually.  In fact, any extraction over 1TB is a pain to do manually.  Running a couple of test extractions will give you an idea of timescales, but you should also get an estimate from Mimecast on their current ingestion times for an end-to-end estimate.

When should we switch off archiving on-premises? It’s always preferable to extract from a static archive so if your Exchange servers can cope, it will be best to stop archiving just before extraction. Mimecast will have probably started Journal Capture by then so you won’t be at risk from a compliance perspective.  It might just be a case of making sure your Exchange mailbox sizes don’t grow too large if you were archiving fairly aggressively beforehand.

What if we’ve stopped archiving on-premises already? That’s great, because your archive is static, but it might mean that you will have content in Exchange that you need to migrate too because you’ll have this gap of time between your archive stopping and Mimecast starting.  If possible, I’d recommend archiving everything into your on-premises archive so it can all be extracted from one place.

If that’s not an option, you’ll have to do an extraction from Exchange. We’ve helped a couple of customers with this recently because they needed to define a date range and exclude stubs from the extraction because stubs will obviously be useless once in Mimecast and users might get confused.

Talking of stubs, don’t forget to delete them from user’s mailboxes after you’ve completed the migration.

Any extra tips?  Migration to Mimecast might be a good opportunity to centralise any other email you’ve got in PST files. Mopping up rogue PST files isn’t that easy, but if you have concerns around PSTs now might be a good time to tackle them.

Can we migrate out of Mimecast?

Yes, but not without technical and/or financial pain.  I guess it’s no surprise that a SaaS vendor wants to keep your business.  As a result, open APIs and no-cost options that let you readily take your data (and your business) elsewhere are not common.

With Mimecast it’s possible to export all emails belonging to an individual user (in batches of 10GB and a maximum of 2GB per file).  We’ve also encountered approaches that involve automating eDiscovery searches and exporting the results (exports are currently limited to searches returning fewer than 50,000 messages).  Both of these approaches are a world of pain if you’re trying to navigate a timely and reliable exit strategy for your valuable email records.

The best route for larger enterprises is to pay Mimecast’s per GB extraction fee.  As I say – it’s painful either way.  The default format you’ll get your precious data in is a big, single-instanced bucket of emails.  You are then left with the challenge of how you’re going to move this into your new email/archive/journal platform of choice.

Click here and find out more about how Essential can help your migration to (or out of) Mimecast..