Email Migration

Every mailbox moves in a single scheduled window. The right choice for a smaller organization on one domain with nothing still tied to an on-premises server. The real ceiling is not a mailbox number published by a vendor — it is how much data moves inside the window you can tolerate, and how many devices have to be re-profiled on Monday morning. We size both before recommending it.

Mailboxes move in batches over days or weeks, usually grouped by department or by site, so the support load arrives in portions a help desk can absorb instead of all at once. The trade-off is a coexistence period where mail flow, calendar lookups and directory data have to work between migrated and unmigrated users. That coexistence work is the part most plans underestimate, so we scope it explicitly.

Some mailboxes stay on-premises while others live in the cloud, sharing one address space with calendar availability visible across both. The right answer when an application still has to relay through the local Exchange server, or when a regulatory position on data location has not been settled. It is also the most operationally expensive of the three to run and to eventually unwind, and we will tell you that before you choose it.

Exchange, hosted Exchange, Zimbra, Lotus Notes, GroupWise, cPanel mail and plain IMAP accounts. Older sources are the ones where folder depth, message encoding and non-standard flags cause surprises, so a legacy source gets a pilot batch and a sample audit before anything is scheduled.

Domain verification on the target, autodiscover records, and a time-to-live reduction staged days before the change so resolvers pick up the new MX record promptly instead of serving a cached answer. We watch inbound mail on both platforms until every sending system has followed, and we confirm registrar access in advance so the cutover date is not held hostage to a forgotten login.

Retention rules, archive location, journaling obligations and any active litigation hold are documented on the source and re-established on the target before the first batch runs, not discovered afterwards. Where HIPAA or a contractual retention term applies, the requirement is written into the migration plan so the evidence trail is intact on both sides.

Once the mailboxes are moved, the old server still holds relay connectors, public folders, certificates and directory attributes that other systems depend on. We keep it running read-only through reconciliation, retire the dependencies in order, and only then decommission — rather than switching it off on cutover night and finding out what needed it.

Tenant-to-tenant consolidation, SharePoint and OneDrive alongside mail, Teams history, and the domain moves that come with a merger have their own considerations beyond mail. Those live on our dedicated page rather than being summarized here.

Workspace changes what users see, how Drive replaces file shares, and which transfer tooling applies. The destination-specific detail is covered on our Workspace migration page, which this page links to directly.