Moving your organisation email without losing a day

Email migration has an unusual property: the failure is not technical, it is that somebody loses a message and cannot prove it existed. The technical part is well understood. The staging is what protects you.

Before anything moves

We inventory what is actually there, which is rarely what the list says. Shared mailboxes nobody remembers creating, forwarding rules set up by somebody who left, a distribution list that half the organisation replies to. All of it has to come across or be deliberately retired, and the decision is yours.

We also lower the DNS time to live a day or two ahead. That is the single change that turns a cutover from a six hour wait into a fifteen minute one.

The copy runs while the old system is still live

Mail is copied to the new platform before anything is switched. Nobody is cut off, nothing is deleted, and if the copy reveals a problem we fix it with your old mail still running normally. This is the step people are tempted to skip, and it is the reason migrations go badly when they do.

The cutover

The DNS record changes and new mail starts arriving at the new platform. A delta sync catches anything that landed in the old one during the changeover, so a message sent in that window is not lost.

We schedule this for the quietest hour your organisation has, and we are on hand through it rather than sending a runbook and hoping.

Afterwards

The old mailboxes stay in place, read only, for an agreed period. That is your safety net. Nothing is deleted on cutover day, because the question "where is that message from Tuesday" always comes on Thursday.

Done this way, most people notice the migration only because they had to sign in again.