The principle
A successful migration is a matter of order: the new mailboxes exist before mail reaches them, and the old hosting stays open afterwards, long enough to copy everything.
The steps
- The day before — lower the lifetime (TTL) of your MX records at your DNS host, so that the switch is quick.
- Order your mailboxes with the same addresses as at the previous provider, and wait for the message announcing that they are open.
- Copy what exists into the new mailboxes — see below.
- Switch the MX — see Point your MX records. New messages now arrive with us.
- Copy again what arrived in the meantime at the previous provider.
- Cancel the old hosting only after checking, mailbox by mailbox, that nothing is missing.
Copying the messages
With Outlook, through a .pst file — the safest method for an existing Exchange or Outlook mailbox.
- In Outlook, with the old account open: File → Open & Export → Import/Export → Export to a file → Outlook Data File (.pst). Tick “Include subfolders”.
- Add the new mailbox to Outlook — see Add your mailbox to Outlook.
- Import/Export → Import from another program or file, choose the .pst, and import into the new mailbox.
Messages, calendar and contacts all follow.
From Gmail or an IMAP account — add the old account and the new mailbox side by side
in Outlook or Thunderbird, then drag the folders from one to the other. For Gmail, enable
IMAP access in its settings first. Gmail's calendar and contacts are exported separately,
as .ics and .csv files, and then imported into Outlook.
What is not copied
Sorting rules, signatures and automatic replies have to be recreated in the new mailbox. Plan for it with shared mailboxes and front desks.
Many mailboxes, or little time
Write to us before you start, with the number of mailboxes, their size and the current provider: we will tell you what can be done and how.