Sizes of mailboxes on 365

Question

We are moving mailboxes on-prem to mailboxes on 365. Licenses are business premium and can have mailbox size of 50GB and 50GB archive mailbox.

But we have also users with a huge mailbox size, like up to 200GB (no archive mailbox). Indeed it is on on-prem so it was no issue at all, but now it is.

Even if we go for the more expensive license it is still restricted to 100GB + 100GB (archive).

Plus, that user is also having multiple shared mailboxes, so the ost (which will later be used) will add more data.

How can this be resolved in practice, not in theory? Does it make sense to

Thanks for your knowledge.

Kurt

Answer 1

Hi @Kurt Stichelmans ,

Welcome to the Microsoft Q&A platform!

Based on your description, migrating a large mailbox from on-premises to Microsoft 365 can be challenging, especially given the size limits. Here are some practical steps to help you manage this transition:

1. Microsoft 365 offers an auto-expanding archive feature that allows mailboxes to grow beyond the standard archive size limit. This can help accommodate larger mailboxes by automatically adding more storage space as needed.
2. Implement retention policies to move older or less frequently accessed emails to the archive mailbox. This can help reduce the size of the primary mailbox and ensure that only the most relevant data is retained in the primary mailbox.
3. For users with extremely large mailboxes, consider splitting their data across multiple mailboxes. This can be achieved by creating additional mailboxes and distributing the data accordingly.
4. For users with multiple shared mailboxes, ensure that these mailboxes are also managed effectively. If the shared mailbox in Microsoft 365 is less than 50GB, a license is not required. If it exceeds this limit, you can assign an Exchange Online Plan 2 license to increase the storage limit.
5. To manage the size of the OST file on the user's device, consider configuring Outlook to only sync a specific range of emails (for example, the last 12 months). This helps reduce local storage requirements on the user's device.

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Please feel free to contact me for any updates. And if this helps, don't forget to mark it as an answer.

Best,

Jake Zhang

Answer 2

For this there is no easy solution. The rules are as is, but some people think the world revolves around them.

I will try to solve it with different shared mailboxes and the user will have to clean his mailbox without contradiction.

Thanks for your clear list.