There are several ways to migrate your messaging system.
This article gives a short introduction to the different options.

The decision you will take will vary depending on several parameters:

  • How much time do you have for the migration?
  • What is the volume of data to migrate?
  • What is the available bandwidth?
  • How long do you estimate the migration to take?
  • Do you want a pilot and leave the pilot in production (= coexistence scenario where some users are migrated and others are not, and they need to be able to communicate and book resources)?
  • How will you organize yourself to train people (training on the new system, change management, etc.)?
  • Do you have to go to each computer and install new software?

Once you have evaluated these points, you’re ready to take your decision.

How do you move from point A to point B and how long will it take?

Let’s discuss the different options you have.

Migration path 1: no data migration

You set up a new system from scratch and do not migrate any data. This has the main advantage of a drastic overhaul and means you won’t come away with full mailboxes.

Migration path 2: big bang

You migrate everybody over a weekend and perform a single migration pass.

Migration path 3: pre-staging migration

You migrate mailboxes during several days and/or weeks. You perform incremental passes.
The last weekend before going live, you perform a final delta pass to complete the migration of mailboxes.

Migration path 4: partial pre-staging

You migrate the last X days of mails (for example 1 month) and go live a Monday morning. Older mails remain available by still allowing users to connect to the old system. You explain to your internal users that the rest of their data will arrive in the incoming weeks/days.