Category Archives: Exchange

Exchange 2013 Mailbox database Disaster Recovery

In Exchange 2010 Microsoft introduced the Database Availability Group to implement redundancy on mailbox server level and mailbox database level. If a mailbox database (or a server) fails, another one can take over. This concept is carried forward into Exchange 2013 and Exchange 2016 and has improved ever since.

There are still customers that do not use a Database Availability Group and rely on a single server and a solid backup software solution. A backup of the mailbox database is created every night and this continue to run for years. You hope. Until disaster strikes…..


I got a call earlier today from a customer. He has been patching his Hyper-V host, and after a reboot his Exchange 2013 server didn’t come up properly. Well, after questioning it turned out that the Exchange server booted correctly, but that only one of three Mailbox databases mounted properly. So, two Mailbox databases (approx. 250 GB in size) seem to be corrupt and this is where the pain begins.

To ‘resolve’ the issue the customer tried to reboot the box again, tried to restore the databases from backup, tried a ‘soft repair’ and tried a ‘hard repair’. No idea what the latter are by the way, but that was according to the customer. But if you know anything about Mailbox databases in Exchange, then you also know that most destruction happens in the first 15 minutes!

If you rely on a single server and a backup solution for restoring services or a disaster recovery scenario you have to know the basics of Exchange database technology. Know what a mailbox database is (except for a large .edb file), know what transactional logging is and how the mailbox database, the transaction log file and the checkpoint file relate to each other. And related to this, it is of utmost importance that you know how to replay transaction log files into a Mailbox database.

Although old, these are good starting points:

Furthermore, you have to know how your backup solution works, and how to restore mailbox database into a production environment. There are streaming backups, but these are rare these days and VSS snapshot backups. You can find more detailed information in the following articles:

Besides the technical knowledge about the Mailbox database technology you have to perform regular ‘fire drills’. Restore a Mailbox database into production, restore using a recovery database, perform replaying of transaction log files, get your hands on ESEUTIL and see what the /G, /K, /P and /R are doing. It will save you a considerable amount of time when you know the technology and the tools, it will reduce risk of data loss and you are able to give a proper planning to your users/manager/customer when the mailboxes are available again.

If you don’t know this you’re playing with fire, and it will backfire to you, believe me!

A reboot is required to complete file operations on ‘exchangeserver.msi’

I already mentioned this in my blogpost about Exchange 2016 CU6 and Exchange 2013 CU17, but when upgrading an existing Exchange 2016 server to Exchange 2016 CU6, the setup application stops after step 5, 6 or 7 (random) with the following error message:

“A reboot is required to complete file operations on ‘E:\exchangeserver.msi’. Reboot the machine, and then run setup again”


After rebooting and restarting the setup application the upgrade finishes successfully.

Rebooting the Exchange 2016 server prior to starting the upgrade process does not prevent this from happening. Also, there’s no difference between Exchange running on Windows 2012 R2 or Windows 2016.

The installation process has been tested by Microsoft and TAP customers, and tests are still conducted. It is somewhat clear what the root cause is for this issue, it is an MSI package that’s causing this issue. Please be aware that the Microsoft setup application executes around 200 MSI packages, and if only one MSI package is having difficulties you can see issues like this. Because of the number of MSI packages it is not possible to check in advance if your server will experience this issue.

At this moment the only solution is to reboot the server when requested and restart the application program.

Exchange 2013 CU17 and Exchange 2016 CU6

On June 27, 2017 Microsoft has released its quarterly updates for Exchange 2013 and Exchange 2016. The current version is now at Exchange 2013 CU17 and Exchange 2016 CU6. Typically I don’t pay that much attention to this, all new developments seem to be for Office 365 and very little developments for on-premises Exchange deployment. But this time there are some interesting things I’d like to point out.

A couple of days before the release of Exchange 2016 CU6 Microsoft blogged about Sent Items Behavior Control and Original Folder Item Recovery. With the Sent Items Behavior Control, a message that’s sent using the Send As or Send on behalf of permission is not only stored in the mailbox of the user that actually sent the message, but a copy is also stored in the delegator mailbox sent items. This was already possible for shared mailboxes, but now it’s also possible for regular mailboxes (like manager/assistant scenarios).

The Original Folder Item Recovery feature is I guess on of the most requested features. In the past (before Exchange 2010) when items were restored after they were deleted, they were restored to their original location. With the Dumpster 2.0 that was introduced with Exchange 2010 this was no longer possible, and items were restored to the deleted items folder. In this case the items had to be moved manually to their original location. With the introduction of the Original Folder Item Recovery the restore of deleted items again takes place in the original folder.

Continue reading Exchange 2013 CU17 and Exchange 2016 CU6

Exchange 2010 hybrid, SMTP, SSL Certificates and Subject Alternative Names

On every Exchange server you need SSL certificates for authentication, validation and encryption purposes. For SMTP you can use the self-signed certificate. Exchange 2010 uses opportunistic TLS, so the self-signed certificate will do in this scenario. If you need to configure domain security (mutual TLS) on Exchange, you need a proper 3rd party SSL certificate for this.

SMTP communication between Office 365 and Exchange in a hybrid scenario is an example of mutual TLS or domain security. A proper 3rd party SSL certificate is needed on your Exchange server.

I was always under the impression that mutual TLS can only use the Common Name of the certificate, which in my scenario is After a previous blogpost there was an interesting discussion (see the comments of this particular blogpost) about this, so now it’s time to do some testing.

Originally I had a Digicert SSL certificate with Common Name, and a Subject Alternative Name entry During the HCW I entered and selected the proper certificate.

It was time to renew my SSL certificate, so I added an additional SAN entry


Continue reading Exchange 2010 hybrid, SMTP, SSL Certificates and Subject Alternative Names

Exchange 2010 Hybrid cannot establish Mutual TLS wrong certificate is used

When configuring an Exchange 2010 hybrid environment a Receive Connector is created on the Exchange 2010 server. This Receive Connector is configured with the FQDN entered in the Hybrid Configuration Wizard (see previous blog post on Exchange 2010 Hybrid) and the source IP addresses of the Microsoft Exchange Online servers. If one of these servers access the Exchange 2010 environment, they end up on the Office 365 Receive Connector (based on the IP address) and the correct SSL certificate is returned. This way mutual TLS is established between Exchange 2010 on-premises and Exchange Online.

It sometimes happens that the wrong certificate is used for SMTP communication between Exchange on-premises and Exchange Online, thus resulting in SMTP mail flow failure between the two.

You can check this in the Exchange Admin Center (EAC) in Exchange Online. Logon to the EAC in Exchange Online, select Mail Flow and click the Connectors tab. You’ll see two connectors. One connector for mail from Exchange 2010 to Exchange Online, and one connector for mail from Exchange Online to Exchange 2010.


Continue reading Exchange 2010 Hybrid cannot establish Mutual TLS wrong certificate is used