Microsoft is unlocking the "Full Potential" of Private Channels in Microsoft Teams: What You Need to Know

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It has been a while since I posted something just about a Microsoft Teams update, as a lot have been Copilot in Teams to be honest. But here is a real Microsoft Teams update I think is worth knowing about, and it involves Security and Compliance as well. Microsoft is rolling out a "major" update to private channels in Teams, starting in late September 2025 and continuing through mid-December. This biggest change in this update is a shift in how private channel data is stored from individual user mailboxes to a dedicated channel mailbox. Not only will this simplifie compliance management, it will also and align private channels with shared channels, making governance and experience more consistent across Teams. This update promises to increase the support up to 1000 channels per team and 5000 members per channel, removing previous limitations. Teams will also allow meetings to be scheduled directly within private channels, enhancing collaboration.  For organizations using Micr...

Lync client may connect to a non federated partner, even if you though it should not.

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Here is an "interesting" observation I did a couple of days ago. The customer has chosen not to allow DNS discovery of federated partners, but will allow federation with selected partners on the allow list. After a while with this configuration, the customer called me and told me they had mixed experiences with the solution. There were times when meetings with a partner (NOT on the allow list) actually would work, even if they expected the meeting to fail.

They asked me to verify the settings, and to investigate why some users reported they could connect to a meeting others couldn't.

This is what I saw on a client who failed to connect:




5 messages. And the interesting one would be the 504 message: "Can not route".



And then the client stops trying, as I would expect it to.

But here is an interesting twist. Log on with the same client from a remote connection (through edge), and then let's see what happens.



The client does not honor the 504 message "Can not route". It continues and connects to the meeting, unexpectedly. How can that be?

The interesting part is what happens after the 504 message. First the client acknowledges the rejection, but then it does something it didn't do on the inside. There is a new invite, trying to connect anonymously:



And this connection is allowed. Quite confusing for the end user, actually. But now they know.


It is important to note the user was allowed for federation in this scenario, but the domain in question was not in the allow list and DNS discovery was not allowed. Also, the organizer on the other side was allowing anonymous invites.