Increase mailbox size with M365 past 100GB with online archive.

If you need more than 100GB of mailbox storage in Microsoft 365, you can use an online archive mailbox to increase your storage capacity. An archive mailbox is a secondary mailbox that can be used to store older emails and attachments. To increase your mailbox size in Microsoft 365 beyond the default 100GB limit and enable an online archive using the Exchange Admin Center, follow these steps:

1. Sign into the Microsoft 365 admin center (https://admin.microsoft.com) using an account with administrative privileges.
2. In the admin center, navigate to the Exchange Admin Center. You can find it under the “Admin centers” section, or you can directly access it using the URL: https://admin.exchange.microsoft.com.
3. In the Exchange Admin Center, click on “Recipients” in the left-hand navigation pane and then select “Mailboxes.”
4. Locate and select the user for whom you want to increase the mailbox size and enable the online archive.
5. In the user’s mailbox properties, click on “…” (More options) under “Mobile Devices.”
6. From the dropdown menu, select “Archive…”
7. In the “Archive” section, select “Enable.”
8. Under “Archive size,” select the desired size limit for the online archive mailbox.
9. Click on “Save” to apply the changes.

Once the changes are saved, the online archive mailbox will be enabled for the user, and they will have additional storage beyond the 100GB limit. This is different than using a local copy of Outlook’s archive feature.

Enabling an archive mailbox may require additional licensing or subscription plans, and that changes may take some time to propagate. Also, keep in mind that large mailboxes can be difficult to manage, so it’s a good idea to regularly review and delete any old or unnecessary emails to keep your mailbox size manageable.

Once you have enabled the archive mailbox, older emails and attachments will automatically be moved to the archive mailbox to free up space in the primary mailbox. You can access the archive mailbox in the same way as the primary mailbox.