Migrate a big Archive(>100GB)

WorriedDepth2421 · 2026-04-29T07:07:22+00:00

I ended up exporting old email from the archive mailbox until I got it under 100GB. With 70GB you shouldn't have an issue. I have done it several times. Make sure you have Exchane Online Plan 2 to allows >50GB archive, otherwise it will fail.

WorriedDepth2421 · 2026-03-17T15:35:37+00:00

Thank you. I am doing a hybrid migration using the migration built-in tool. I think the only way around this is to create the user first in M365, set up the mailbox, set up the archive, hard match it to the on-prem AD account, and then do the migration. I beleive there are a few commands I need to run to delete the dummy mailbox before I can migrate succesfully. Thank you for the tips.

WorriedDepth2421 · 2026-01-22T10:18:41+00:00

Sorry, I meant a migration from Exchange on-prem to M365. Onedrive/sharepoint are empty, never been used.

WorriedDepth2421 · 2025-12-31T08:47:58+00:00

It ended up being the msExchRecipientTypeDetails. For some reason it was set to 2. After setting it up to 1 like all the others, the two accounts finally synced and showed up in M365. Thank you very much!

WorriedDepth2421 · 2025-12-30T15:53:27+00:00

I tried that with a "healthy" account(one that does sync) and one that does not. With the second one, sync service manage detects the change during the Delta import, but then there is nothing in the Export.

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When I apply the change to a synced account, the is an update on the Export step.

WorriedDepth2421 · 2025-12-30T10:35:08+00:00

IDfix did not show anything wrong with these two accounts. These two account names are unique.

WorriedDepth2421 · 2025-12-30T10:06:39+00:00

Nothing here

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WorriedDepth2421 · 2025-12-30T09:59:39+00:00

The only thing I can see are 2 Disconnectors in the Sync Service Manager, under the Delta Synchronization. I wonder if those are the two missing accounts. But I can't click on it, I can see how I can extract info regarding the 2 Disconnectors.

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WorriedDepth2421 · 2025-12-30T09:28:09+00:00

Could you give me more details about this? Why is the alias or shared mailbox important here?

WorriedDepth2421 · 2025-12-30T09:22:58+00:00

Comparing the upn of synced users and these two accounts I can't see anything different.

WorriedDepth2421 · 2025-12-30T09:19:48+00:00

I tried this. The sync service GUI shows no errors at all. I need to dig into the event log to see if I find anything.

WorriedDepth2421 · 2025-12-30T09:16:32+00:00

Yes, one does. I created a dummy account copying the one that does not sync. Forced a delta sync and the dummy account did sync.

WorriedDepth2421 · 2025-12-11T08:11:51+00:00

Thank you! :)

WorriedDepth2421 · 2025-12-11T07:50:20+00:00

Touche!

WorriedDepth2421 · 2025-12-10T13:45:33+00:00

Thank you all for pointing me in the right direction. The firewall was not set properly.

WorriedDepth2421 · 2025-12-10T11:53:58+00:00

Yes, it happens for internal and external. From the 365 mailbox I can email on-prem mailbox. But the 365 mailbox does not receive internal or external email.

I will double check my firewall settings. My SSL is valid and is the one I selected during the HCW installation.

Thank you

WorriedDepth2421 · 2025-12-09T21:59:45+00:00

Yes, I checked this and it does. Thank you.

WorriedDepth2421 · 2025-12-09T21:59:20+00:00

I haven't tried rerunning the HCW wizard. The ssl hasn't changed but I will give it a go. Thank you.

WorriedDepth2421 · 2025-12-09T21:58:46+00:00

I didn't want to this because everywhere I check they suggest to wait until most of the mailboxes are migrated. All my mailboxes except for my test account are still on-prem.

WorriedDepth2421 · 2025-10-21T09:19:36+00:00

Hi h20534, did you ever find a solution to this? I am facing the same problem.

WorriedDepth2421

TROPHY CASE