You may see the following error in EMC: “An error caused a change in the current set of domain controllers”. Get-DatabaseAvailabilityGroup shown below, is just one of the failing functions:

This is usually combined with a slow (laggy) EMC in general.

The problem can occur after having demoted Domain Controllers in your domain that EMC wants to talk to. Using Set-ADServerSettings has no effect on this problem.

To resolve the issue, simply delete the following file (the file has no extension):

C:\Users\<user>\AppData\Roaming\Microsoft\MMC\Exchange Management Console

Now your EMC is responsive again and will not show DC related errors.

Thanks to Søren Reisz for testing!

On rare occasions you may experience that spam messages are (consistently) delivered to the Inbox folder instead of the Junk E-mail folder even though it is rated at SCL: 9

The graphic below shows the properties of an e-mail rated at SCL: 0 as an example.

If you get mails with SCL level 5-9 in your inbox even though you enabled junk e-mail filtering in Outlook as shown below:

Then open OWA Settings, disable filtering and click save. Then re-enable filtering and save.

Now spam should go to your Junk E-mail Folder…