Tag Archives: Exchange Online

MigrationTransientException: Target database GUID cannot be used (Mailbox database size limits in Exchange Online)

If you are designing Exchange 2016 (or have been designing Exchange 2013) environment you are aware of the The Exchange 2016 Preferred Architecture (https://blogs.technet.microsoft.com/exchange/2015/10/12/the-exchange-2016-preferred-architecture/) and articles like Ask the Perf Guy: How big is too BIG? (https://blogs.technet.microsoft.com/exchange/2015/06/19/ask-the-perf-guy-how-big-is-too-big/) which explain pretty much how to design an Exchange solid (and large) Exchange environment.

When it comes to Mailbox databases, the recommended size limit for non-replicated databases is 200GB and for replicated databases 2 TB (when running 3 or 4 copies of a Mailbox database).

One can only guess how Microsoft has designed their Exchange servers in Exchange Online, but we can assume that the Preferred Architecture is written with their Exchange Online experiences in mind.

Sometimes error messages that are generated in Exchange Online can reveal more information. While moving mailboxes from Exchange 2010 to Exchange Online in a hybrid configuration the following error message was returned in a migration batch for a number of Mailbox databases:

Error: MigrationTransientException: Target database ‎’07bdf507-ab94-479b-aeb6-1bfef1458c4c‎’ cannot be used: Current database file size: 1502835900416 Current space available inside database: 100237312 Allowed database growth percentage: 90 Maximum database file size limit: 1622722691784 Is database excluded from provisioning: ‎’False‎’. –> Target database ‎’07bdf507-ab94-479b-aeb6-1bfef1458c4c‎’ cannot be used: Current database file size: 1502835900416 Current space available inside database: 100237312 Allowed database growth percentage: 90 Maximum database file size limit: 1622722691784 Is database excluded from provisioning: ‎’False‎’.

Obviously it’s telling us the migration cannot proceed since the target Mailbox (in Exchange Online!) has reached its size limit. The following sizes are reported:

  • Current database file size: 1502835900416 (1,502,835,900,416 bytes, approx. 1.5TB)
  • Current space available inside database: 100237312 (100.237.312 bytes, approx. 100MB)
  • Maximum database file size limit: 1622722691784 (1.622.722.691.784 bytes, approx. 1.6 TB)

So, the maximum size limit for Exchange 2016 in Exchange is not really used in Exchange Online, but it’s getting close, which is interesting to see.

What I don’t understand is why this issue occurs in the first place. To me it looks like a failing part in the provisioning service but I have to admit I’ve never seen this before in the last couple of years so I expect it’s only one Exchange server that’s failing here.

Exchange Online PowerShell multi factor authentication (MFA)

It’s a good thing to enable multi-factor authentication (MFA) for Office 365 administrators. For web based management portals this is not a problem, just enter your username and password, wait for the text message to arrive, enter it in the additional dialog box and you’re in.

For PowerShell this has been more difficult, but MFA for PowerShell is available as well for some time now. When you login to the Exchange Admin Center and select hybrid in the navigation pane you can configure a hybrid environment (first option) or install and configure the Exchange Online PowerShell MFA module.

Click on the second configure button, and in the pop-up box that appears click Open to start the installation of the PowerShell module:

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Continue reading Exchange Online PowerShell multi factor authentication (MFA)

Moving from Exchange 2010 to Office 365 Part II

In my previous blogpost, I’ve discussed the prerequisites for moving from Exchange 2010 to Office 365 when using Directory Synchronization (using Azure AD Connect). In this blogpost I’ll discuss how to create an Exchange 2010 hybrid environment.

Exchange 2010 Hybrid

Now that Directory Synchronization is in place using Azure AD Connect we can focus on connecting the on-premises Exchange environment to Exchange Online, this a called an Exchange Hybrid Configuration.

Hybrid configurations can consist of Exchange 2010, Exchange 2013 or Exchange 2016 or a combination of versions, so it is possible to have an Exchange 2010 and Exchange 2013 coexistence scenario on-premises, and connect this to Exchange Online. However, when using multiple versions of Exchange in a Hybrid configuration there’s always add complexity, and when configured incorrectly you can get unexpected results. Therefore, I typically recommend using only one version, so if you’re running Exchange 2010 on-premises, there’s no need to add an Exchange 2013 or Exchange 2016 server to your configuration, just as a ‘hybrid server’. Despite what other people tell you, there’s no need to add a newer version, and Exchange 2010 Hybrid is fully supported by Microsoft. Better is to create an Exchange 2010 hybrid environment, and when the mailboxes (or most the mailboxes) are moved to Office 365 upgrade your existing Exchange 2010 environment to Exchange 2016. But that might be an interesting topic for a future blog post Smile.

Basically, we will create the following configuration (again, there is no Exchange 2016 server installed in the existing organization):

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Figure 14. Exchange 2010 hybrid configuration.

Continue reading Moving from Exchange 2010 to Office 365 Part II

Moving from Exchange 2010 to Office 365

There are a lot of articles on the Internet on how to create a hybrid environment, where Exchange 2016 is connected to Office 365. Now that’s fine, but when you’re running Exchange 2016 you most like are NOT going to move to Office 365 anytime soon I guess. If you are running Exchange 2010 chances are that you will move to Office 365 (soon), but there aren’t that much articles about moving from Exchange 2010 to Office 365. And a lot of the articles available don’t have the right approach I’m afraid, and will result in you (the customer) having to pay way too much money to your system integrator.

In this article, I’ll try to outline the recommended approach when moving from Exchange 2010 to Office 365 in a hybrid scenario. With Azure AD Connect for synchronization purposes. Cliffhanger: I’m not going to install Exchange 2016 into the existing Exchange 2010 environment Smile

Existing Exchange environment

Our organization is called Inframan and they have their own on-premises Exchange 2010 environment which they have been running for 5 years now without too much issues. There are internal Outlook clients using Outlook 2010 and higher, and there are external clients using Outlook Anywhere. There are also mobile clients using ActiveSync to connect to their Mailboxes. Of course, there is Outlook Web Access, but POP3 and IMAP4 are not used.

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Figure 1. Overview of the Inframan Exchange 2010 environment.

Continue reading Moving from Exchange 2010 to Office 365

Disable automatic forwarding in Office 365

By default automatic forwarding and automatic replies of email messages is turned on in Exchange Online (Office 365). You can turn this of in the Exchange Admin Center of Exchange Online (https://outlook.office.com/ecp).

Logon using your tenant administrator, select mail flow in the navigation menu and select the remote domains tab.

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Open the Default remote domain and deselect the Allow automatic replies and Allow automatic forwarding checkboxes under Automatic replies.

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When you click Save automatic forwarding and automatic replies will be turned off in your Office 365 tenant. Please be aware that it can take some time before the settings becomes active (I think due to replication issue).