IMAP to O365 migration question

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martyyn

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#279630 29-Oct-2020 09:52

I'm looking to migrate about 12GB for seven account from a US shared server account (don't ask) to a new O365 account.

Everything is ready to go, the O365 account is set up, the users have appropriate licenses and the initial migration is synced and successful with a perfect consistency score. So I'm ready to make the MX changes.

But when I log into Outlook online for the main admin account it only shows email up until 4pm yesterday. There was email received on the account after 4pm and also this morning.

The start time shows as 10/28/2020 8:12:52PM - which I assume is UTC time and the last synced time is 10/28/2020 4:11:23AM.

So how often is the synchronisation run ? All the instructions I find online just say it "synchonises" and you delete the job once you confirm the MX change has taken effect.

What am I missing ?

fearandloathing

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#2593160 29-Oct-2020 11:23

Is your source rate limiting, I suspect this is the culprit.

martyyn

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#2593481 29-Oct-2020 16:29

I just left everything as the default settings.

Everything is set up on the new accounts now but there are still emails which arrived this morning to the old account which have not arrived in O365.

fearandloathing

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#2593493 29-Oct-2020 17:07

It’s probably not exchange online doing the throttling for instance Google limits migration to 2.5 GB per user per day.
Your IMAP mail source server may also have a similar limit.

We have had gmail IMAP migrations run for over a week with large mailboxes. Unfortunately it can be just a case of hurry up and wait.

martyyn

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#2593822 30-Oct-2020 09:43

Fair enough. Thanks.

fearandloathing

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#2593825 30-Oct-2020 09:54

In case, that didn't quite answer your question, Exchange Online will do a sync every 24 hours.

martyyn

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#2593908 30-Oct-2020 12:04

So have we jumped the gun a little in updating the MX records before the migration is completed ?

There are still a couple of emails from yesterday morning which don't appear in the Inbox.

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fearandloathing

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#2593909 30-Oct-2020 12:16

martyyn:

So have we jumped the gun a little in updating the MX records before the migration is completed ?

There are still a couple of emails from yesterday morning which don't appear in the Inbox.

No, you haven't jumped the gun; updating the MX records now is fine, I would have done the same in that situation, as long as the old mail is syncing though slowly.

martyyn

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#2593961 30-Oct-2020 14:14

The status in Exchange Admin has changed from Synching to Synced and the report state no issues with perfect data consistency but the numbers in the report are the same.

It also state the last synced time as 28/10 9:16pm, so is there somewhere else I should be checking ?

fearandloathing

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#2593978 30-Oct-2020 14:43

Synced just means the initial sync has completed, the process will still do incremental syncs every 24 hours. Leave it over the weekend and check on Monday.

Jogre

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#2601909 11-Nov-2020 15:47

Should always do a delta sync after MX changes anyway in case anything comes through while new MX is replicating.

Jono Green

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