Dear Elmer_G21,
As an Independent Advisor and community user, I'll help you with your question.
In below document you will have all IP Range for Microsoft Teams and Office 365 technologies, so you have to update your Proxy / Firewall white list with those information:
https://docs.microsoft.com/en-us/microsoft-365/...
Regards,
Renzo.
Microsoft Learn
learn.microsoft.com › en-us › answers › questions › 826371 › whitelist-a-domain-for-teams-online-in-a-federated
whitelist a domain for Teams online in a federated environment. - Microsoft Q&A
You can configure the External Access in your organization by adding the particular domain into the Allow list via Teams Admin Center: In the Teams admin center, go to Users > External access.
Microsoft Learn
learn.microsoft.com › en-us › answers › questions › 928643 › whitelist-external-domain-for-teams-communication
whitelist external domain for teams communication - Microsoft Q&A
You are going to want to enable ...ommunicate-with-users-from-other-organizations ... Under Users > External Access > Choose which external domains your users have access to: > Choose your setting of allowing external ...
Solutions2Share
solutions2share.com › home › blog › blacklist and whitelist external domains in microsoft 365 – how to control guest access effectively
How to Blacklist and Whitelist External Domains in M365?
April 4, 2024 - Many organizations collaborate daily with external partners, suppliers, or clients in Microsoft Teams. But what happens when someone from an unknown or unwanted domain gains access? Uncontrolled guest access can lead to security risks and compliance violations. The good news: Microsoft 365 allows you to blacklist or whitelist external domains – and with External User Manager, you can even automate this process.
Reddit
reddit.com › r/microsoftteams › users | external access | allow only specific domains
r/MicrosoftTeams on Reddit: Users | External Access | Allow only specific domains
July 31, 2023 -
We want to block chat to external domains unless whitelisted but the documentation and UI appear to conflict with an older thread.
The UI would indicate to me that only if external domains are allowed that you can add users to meetings and the documentation specifically says that external users will be considered anonymous when joining a meeting - which is not ideal.
Can anyone shed any light on exactly how this works?
Top answer 1 of 2
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This seeing you have highlighted will have zero impact on meeting attendees. It simply does as you want, and restricts users from having peer to peer chats to only external users of domains you have added to that list.
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An anonymous user is not the same as an external user. Any external user comes from a known, specific external domain which you either have allowed or blocked (or carte blanche allowed or blocked all external domains). An anonymous user (a status which does relate specifically to meetings) is a user of unknown origin where there is no way to determine their identity. This could be users joining from the web client without signing in (think interview candidates), instead joining as a "guest" and choosing whatever name they like to be displayed, [EDIT: or a user from a blacklisted domain]. It could also be users dialing into a meeting with just the conf bridge number and meeting pin (only know info is a phone#, so they are anonymous). These users are "anonymous" because there is no way for the system to determine if they are or are not one of the users invited by the organizer [EDIT: or because they are homed in a domain that you do not "trust" according to your domain blacklist]. https://learn.microsoft.com/en-us/microsoftteams/anonymous-users-in-meetings
Microsoft Learn
learn.microsoft.com › en-us › microsoftteams › trusted-organizations-external-meetings-chat
IT Admins - Manage external meetings and chat with people and organizations using Microsoft identities - Microsoft Teams | Microsoft Learn
To block specific domains, do the following steps: In the Teams admin center, go to Users > External access.
Practical 365
practical365.com › home › teams › building a teams external access allow list from external chats
Building a Teams External Access Allow List from External Chats
November 8, 2023 - By default, Teams allows users ... other Microsoft 365 tenant. The solution to something like the GIFShell exploit is to restrict Teams external access to an allow list (whitelist) of known tenants. The problem then becomes how to populate the allow list. At the time, I suggested that organizations could make a start by building a list of the domains that guest ...
Microsoft Learn
learn.microsoft.com › en-us › answers › questions › 1148258 › whitelist-teams-application-domain-to-allow-micros
Whitelist Teams Application Domain to allow Microsoft Login Page to be embedded - Microsoft Q&A
Hi, We have a ms teams extension application that can be loaded as a tab. In the tab, we are using an iframe to load another custom application. This custom application has a trust established with azure to allow login through microsoft. When…
CleanBrowsing
cleanbrowsing.org › help › docs › domains-to-allow-for-microsoft
Domains to Allow for Microsoft – CleanBrowsing Help
To help, this guide will list some ... All with fast, privacy-respecting DNS. Start Filtering Here → · All CleanBrowsing customers can use the Custom Allow feature to whitelist as many domains as they wish....
Microsoft Learn
learn.microsoft.com › en-us › answers › questions › 995816 › external-domain-is-whitelisted-in-our-environment
External domain is whitelisted in our environment but users are unable to chat over teams - Microsoft Q&A
... Could you check that the external access settings are allowed for all external domains as shown below? The steps are as follows : In the Teams admin center > > Users> >External access > > Allow external domain
Netify
netify.ai › home › resources › applications › microsoft teams
Microsoft Teams - Domains, IPs and App Information
Details on Microsoft Teams domains and IP networks. You can use this information to manage or block Microsoft Teams apps, web access and more.
Microsoft Learn
social.technet.microsoft.com › Forums › en-US › 133d6c98-cf62-463f-be9a-ebdda4f0ca3f › about-whitelisting-domains-for-guest
About Whitelisting Domains for Guest | Microsoft Learn
But if you want to remove all those existent guests whose domains are now blocked/not-allowed, then as Vasil has already advised, you'll need to manually remove them. Regards, Burak V. ... No, it's not going to be deleted, you will have to remove them manually. ... Agree with Burak V., this setting has no impact on the invited guest account. I have tested in my environment, the result is verified. As a supplement, you can learn more about authorizing guest access in Microsoft Teams by this article: /en-us/microsoftteams/teams-dependencies.
Microsoft Learn
learn.microsoft.com › en-us › answers › questions › 515416 › which-ips-urls-and-port-numbers-to-be-whitelisted
Which IP's, URL's and port numbers to be whitelisted for real time communication for MS teams in firewall and network from below docs for teams in our network for entire tenant? - Microsoft Q&A
Which IP's, URL's and port numbers to be whitelisted for real time communication for MS teams in firewall and network from below docs for teams in our network for entire tenant? Link:…
Microsoft Learn
learn.microsoft.com › en-us › defender-office-365 › tenant-allow-block-list-teams-domains-configure
Block domains in Microsoft Teams using the Tenant Allow/Block List - Microsoft Defender for Office 365 | Microsoft Learn
Teams and Skype for Business users in external organizations must be Allow all external domains or Block only specific external domains. Allow my security team to manage blocked domains must be On.
Microsoft Community
techcommunity.microsoft.com › microsoft community hub › communities › products › microsoft teams › microsoft teams
Building a Teams External Access Whitelist from External Chats ...
A Teams external access whitelist controls the domains that users can connect to for federated chats. Organizations often limit federation using a whitelist...
Microsoft Learn
learn.microsoft.com › en-us › answers › questions › 1624884 › is-there-a-maximum-number-of-entries-in-the-whitel
Is there a maximum number of entries in the whitelist for Teams external access? - Microsoft Q&A
you need to select "Allow only specific external domains" and add all of them to the allowlist. How many entries can this list hold? Many thanks and best Regards. Microsoft Teams | Microsoft Teams for business | Other · Microsoft Teams | Microsoft ...
Topedia Blog
blog-en.topedia.com › startseite › microsoft teams now supports per-user external domain access policies
Microsoft Teams now supports per-user external domain access policies | Topedia Blog
October 14, 2025 - Set-CsExternalAccessPolicy -Identity "Topedia External Access Policy" -AllowedExternalDomains @("demo1.tam365.com") -CommunicationWithExternalOrgs "AllowSpecificExternalDomains" Define a domain whitelist in an external access policy
Practical 365
practical365.com › home › teams › update teams external access configuration with powershell
Teams External Access Domain Updates with PowerShell
October 21, 2023 - But the main issue seems to be with “Set-CsTenantFederationConfiguration -AllowedDomainsAsAList”. If I well understand, AllowedDomainsAsAList was only working with the old SkypeForBusiness PS module. With some help : https://learn.microsoft.com/en-us/answers/questions/1160191/whitelist-a-domain-for-teams-online-in-a-federated
Reddit
reddit.com › r/office365 › adding external users to teams/channels but restricting domains?
r/Office365 on Reddit: Adding external users to Teams/Channels but restricting domains?
November 19, 2021 -
We'd like to allow our users to setup Teams/Channels and be able to invite external guests only from specific external domains.
From what I can see Guest access is all or nothing it's either on or off and there doesn't seem to be an option to specify the domains.
Can I do this and if so where please?
Jas
Top answer 1 of 3
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I believe if you restrict the external collaboration settings in the Azure AD portal it will override the teams guest rules. So rather then allowing guests from all domains it would only allow the ones set in the Azure AD.
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Look at the Teams admin center in O365. You can whitelist which domains you want there.