Migrating mailboxes to O365

[neonetman]

I recently set up a hybrid configuration for our Exchange, aiming to migrate all our staff mailboxes to O365, whilst leaving student mailboxes on premises.

 

I'm having some big issues with getting mailboxes to migrate.. some have gone fine, whilst others fail part way through with "Too many transient failures". I'm struggling to work out what is causing this, and how to resolve it.

 

Can anyone suggest how I can progress with this, as it has now been flagged as a high priority project

[supportman]

Just export them to PST then re-attach with the new email account. We did this in a large secondary for about 150 staff and all was done in 48hrs.

 

I don't understand why you would choose hybrid either, full O365 surely is the way forward.

Edited November 30, 2020 by supportman

[chaplic]

You can get detailed logs out of the migration tasks which will give you a clue. If mailboxes have been around a while, and especially if there originated in another email system there will be some soft corruption - often in calendars. You can increase the limit of allowed items. IME such problems are not visible to the user already so no harm done in dropping them.

 

Or the error could be infrastructure side, e.g. load balancer, your exchange servers or sometimes MS itself.