Office 365

This week was a big week for Exchange. Microsoft released its sixth cumulative update for Exchange 2019 as well as a cumulative update for Exchange 2016. At the time of writing, there is no cumulative update for Exchange 2013.

As always, test these updates in a lab first! I recommend checking out this 7-part guide on configuring Exchange in your lab. It doesn’t take much to get one going.

The updates are as follows:

Exchange 2019 Cumulative Update 6 (VLSC)| KB4556415

Exchange 2016 Cumulative Update 17 | KB4556414 | UM Language Pack

So, what’s new in these Cumulative Updates?

In this series of cumulative updates, Microsoft added thirteen new blocked file types for use with the OWA Mailbox Policy. The additions included several scripting extensions, including many python file types such as .py, .pyc, and .pyo. For a full list of the new extensions, check the following article.

These cumulative updates also correct an issue when using the Restore-RecoverableItems command in a pipe. We covered the cloud-exclusive GUI version of this command in an article earlier this week. Be sure to check it out.

Companies leveraging Hybrid Modern Authentication will also want to take note of these updates as they fix unexpected authentication prompts during certificate rollovers.

Customers leveraging Edge Transport will also want to take note as these updates resolve a situation where Edge Transport servers may become unresponsive due to deadlock in the shadow redundancy manager.

For a full list of all fixes, be sure to check out the KBs KB4556415 and KB4556414.

Recover deleted mail using the new Exchange Admin Center in Office 365

In the last quarterly update, we covered the new Exchange Admin Center in Office 365. Exclusive to the new admin center is the ability to recover deleted items back into a user’s mailbox. This process has been available using PowerShell for some time.

Keep in mind you can only recover up to the limit of your single item recovery policy. By default, this is 14 days in Office 365, but can be increased to 30 days (although you will need to set this ahead of time).

You can read more about how to recover deleted items in the following article.

Preventing Reply-All Storms in Exchange Online

Microsoft has added a new feature to combat reply-all storms. These storms are particularly prevalent when numerous people execute a reply-all to a massive distribution list.

Microsoft’s initial reply-all protection will block replies to an email thread for 4 hours if it detects more than ten reply-all messages within 60 minutes to a thread with over 5,000 recipients.

The eleventh sender will receive a non-delivery report titled Reply-All Storm Protection with the reason the message was blocked.