It usually starts with the following question: Is there a way to release the license of an Exchange Online user that left the company, but at the same time, keep the mailbox content? To get this done...
Updated Jul 01, 2019
Version 3.0
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@Jeff ==> a 100GB mailbox converted to a Shared keeps its mailbox limits + nowadays, SharedMailboxes are 100 GB, no longer 50GB. At least in a few customer Tenants I have access to - and as far as I can tell.
A Shared isn't a so bad solution, easier to manage for some people and doesn't require E3+ or Exchange Online Archiving.
@Benoit, the following article will provide a better overview on the things that you know about shared mailboxes:
https://blogs.technet.microsoft.com/exchange/2018/06/21/correcting-shared-mailbox-provisioning-and-sizing/
Answering to you affirmation, with few words, there were cases in which Microsoft provisioned Shared MBXes with 100 GB in size. Microsoft corrected this, and, if a Shared MBX has more than 50 GB in size, it has to have a proper license assigned to it.
Also, on the following article you can find more details about Archive MBXes attached to Shared MBXes:
https://docs.microsoft.com/en-us/office365/servicedescriptions/exchange-online-service-description/exchange-online-limits#storage-limits-across-office-365-options
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Shared mailboxes don't require a separate license. However, without a license, shared mailboxes are limited to 50 GB. To increase the mailbox size, an E3 or E5 license must be assigned. This will increase the mailbox to 100 GB. If you want to enable the archive mailbox or put a Litigation Hold on a shared mailbox, then an Exchange Online Plan 2 license or an Exchange Online Plan 1 with Exchange Online Archiving license is required. If you enable the archive mailbox and auto-expanding archiving for a shared mailbox, additional storage is automatically added when the 100 GB storage capacity for the archive mailbox is reached.
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- Oh yes I remember now! Thanks for the refresher.