One of the most common issues with migrating to Office 365 is that there are a lot of small and medium businesses that rely on migration. It is not an easy thing to perform, but ensuring your data changes to servers on-premises should be performed in the right manner.
A lot of users have reported that they encountered “Mailbox size exceeds target quota” during the migration process. Allow us to help with your query, and we will share some troubleshooting steps to fix your error. Without further ado, let’s check it out. Troubleshooting for “Mailbox size exceeds target quota” Mailbox size of 6.527 GB (6,834,336,719 bytes) exceeds the target quota of 2 GB (2,147,483,648 bytes).
Check the Enabling of the mDBUseDefaults attribute.
Check this from the on-premises Active Directory/Exchange server, which is active during the sessions of Active Directory users and computers.
- Open the administrative tool, and then head over to Active Directory users and computers.
- Now, change the view option to Details view.
- Click on View from the navigation panel, and then choose Advance Features.
- It will pop up a new window where you can tweak some of the attribute settings.
- After that, choose the users and then right-click on them.
- Choose Properties, and then from the Properties window, choose the Attribute Editor tab.
- There you have the mDBUseDefaults attribute, and then ensure the value is set to false.
- For this, you have an edit button in the pop-up window of mDBUserFDefaults. Simply set the value from true to false.
- Click OK to save your action.
Now retry the migration.
Starting with loading and logging in to the Exchange Admin Centre (EAC), begin migrating Microsoft Office 365 to a different database according to your on-premise Exchange server.
- On the Recipient of Exchange Admin Centre, click on the “+” icon button, and then choose Move to a different database.
- Choose the users for which you want, and click on Next to proceed next.
- Assign the name to your New Migration Name Box, and then choose the following mailbox, archive, or both based on your requirements.
- After that, it will ask you to select the dataset where you want to migrate your mailbox and the target archive.
- This was your database for the Mailbox archive; use the correct target database to avoid delay and error.
- Once you finish setting up this, you can start retrying the Mailbox Import.
Check your mailbox quote for the migration to Office 365.
It is important to check because if there is any limit on your mailbox, you won’t be able to migrate. For this, you can use Get-Mailbox. Where it will display if there is any quota exceeded on your mailbox server. However, you are required to use Exchange Online PowerShell with active connectivity. Use the following command to check the actual Office 365 limit:.
- Get-Mailbox <email address> | FL
- This will show you all the details of the mailbox. Check the following fields:
- Issuewarningquota
- Prohibitsendquota
- Prohibisendrecivequota
If you have any quota limit applied to your mailbox, then you can tweak the setting by using the following command example: Not to mention, you can configure based on your demand.
Set -mailbox <email address> -prohibits sendquota <size in GB, example: 10GB> -prohibitsendreceivequota <size in GB, example: 10GB> -issuewarningquota <size in GB, example: 10GB>
Check your Microsoft Office subscription.
There is a different limit for the subscription model you have signed up for; for Office 365 Business and Stand, it’s 50GB. On the other hand, with the Enterprise License, you have 100GB, and the Small Subscription has 2GB of a Quota Limit to be used during active subscriptions.
Migrating to Office 365 and working with Exchange on the Premise server, but comes with a bit of hassle. To have a seamless experience, check everything before doing the migration.