How long does the Online Archive last after converting a mailbox to a shared mailbox?

Question

Hello,

Lets say if a user account had an Online Archive license (included in MS365 BP or E3/E5) and the account was converted to a shared mailbox and the MS licenses were removed, how long will the archive be available?

The standard message when disabling the archive says 30 days, but I've repeatedly encountered situations where the online archive in a shared mailbox without a license was still accessible after >6 months.
But in other cases it was cleared after a couple of months.

No retention policies were assigned.

Answer 1

Hi Allan Stark

Thank you for helping me clarify my misunderstanding.

Typically, the Online Archive remains accessible for up to 90 days after the license is removed.

However, Microsoft may retain it for up to 180 days, depending on internal cleanup cycles. The commonly mentioned 30-day period is a minimum grace period, not a guaranteed deletion timeline.

That said, it's important to understand the official Microsoft policy:

Once a license is removed, the archive mailbox will be disabled immediately, and the archive will enter a 30-day grace period

Manage In-Place Archives in Exchange Server | Microsoft Learn

After this period, the archive becomes non-compliant and unsupported, meaning it is at risk of permanent and unrecoverable deletion at any time.

Additionally, I'd also like to share a referral article as below: 

Data retention, deletion, and destruction in Microsoft 365 - Microsoft Service Assurance | Microsoft Learn

The archive may remain accessible for longer than 6 months, especially in scenarios where the mailbox size is below 50GB and no retention policies are in effect. However, these are exceptions and not guaranteed behavior.

As a forum moderator's role and access, unfortunately that I don’t have access to internal tools directly to help provide you exactly answer with your case, I can only provide information grounded in official Microsoft documentation and general service behavior based on my research and knowledge. However, if you'd like a deeper analysis of a specific case, I recommend raising a support ticket through the Microsoft 365 Admin Center. The support team can access to internal tools that can help identify the exact reason for extended retention.

I hope this information proves useful. If you have any questions or need further clarification, feel free to leave a comment below!

Answer 2

Hi Allan Stark

Thanks for reaching out to Microsoft Q&A forum.

According to my understanding, and as you have noted, an archive mailbox requires an active license to remain accessible. However, in the scenario where the mailbox has been converted to a shared mailbox, it is important to note that shared mailboxes do not require a license for access or validation. Therefore, provided that delegated access is configured (users cannot sign in to a shared mailbox directly, instead, they must access it through their own Outlook or Outlook Web App account) and the total mailbox size does not exceed 50GB, the shared mailbox can continue to be used without a license.

About shared mailboxes - Microsoft 365 admin | Microsoft Learn

I hope this information is helpful. Please feel free to let me know in the comment section if you need any further details.

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