{"id":14667,"date":"2026-01-24T10:01:24","date_gmt":"2026-01-24T01:01:24","guid":{"rendered":"https:\/\/m365jp.net\/?p=14667"},"modified":"2026-01-24T10:06:10","modified_gmt":"2026-01-24T01:06:10","slug":"mc1200058-updated-microsoft-defender-for-office-365-admins-can-block-external-users-in-microsoft-teams-from-defender-portal","status":"publish","type":"post","link":"https:\/\/m365jp.net\/index.php\/2026-01-24-mc1200058-updated-microsoft-defender-for-office-365-admins-can-block-external-users-in-microsoft-teams-from-defender-portal","title":{"rendered":"MC1200058 | (Updated) Microsoft Defender for Office 365: Admins can block external users in Microsoft Teams from Defender Portal"},"content":{"rendered":"<div class=\"postie-post\">\n<div>\n<hr>\n<table id=\"section\">\n<tbody>\n<tr>\n<th width=\"95%\">MC1200058 | (Updated) Microsoft Defender for Office 365: Admins can block external users in Microsoft Teams from Defender Portal<\/th>\n<\/tr>\n<\/tbody>\n<\/table>\n<hr>\n<table id=\"data\">\n<tbody>\n<tr>\n<th>Classification<\/th>\n<td>stayInformed<\/td>\n<\/tr>\n<tr>\n<th>Last Updated<\/th>\n<td>01\/24\/2026 00:51:04<\/td>\n<\/tr>\n<tr>\n<th>Start Time<\/th>\n<td>12\/19\/2025 07:08:07<\/td>\n<\/tr>\n<tr>\n<th>End Time<\/th>\n<td>03\/30\/2026 08:00:00<\/td>\n<\/tr>\n<tr>\n<th>Message Content<\/th>\n<td>\n<p>Updated January 23, 2026: We have updated the timeline. Thank you for your patience.&nbsp;<\/p>\n<p><b>[Introduction]<\/b><\/p>\n<p>  <\/p>\n<p>We\u2019re introducing an <b>integration between Microsoft Teams and Microsoft Defender for Office 365<\/b> that allows security admins to manage blocked external users in Teams through the  <b>Tenant Allow\/Block List (TABL)<\/b> in the <b>Microsoft Defender portal<\/b>. This centralized approach enhances security and compliance by enabling organizations to control external user access across Microsoft 365 services.<\/p>\n<p>This message is associated with Roadmap ID&nbsp;<a href=\"https:\/\/www.microsoft.com\/microsoft-365\/roadmap?filters=&amp;searchterms=542189\" target=\"_blank\">542189<\/a>.<\/p>\n<p><b>[When this will happen:]<\/b><\/p>\n<p>  <\/p>\n<p>General Availability (Worldwide): Rollout begins mid-February 2026 (previously early January) and is expected to complete by end of February 2026 (previously mid-January).<\/p>\n<p><b>[How this affects your organization:]<\/b><\/p>\n<p>  <\/p>\n<p><b>Who is affected:<\/b> Organizations using Microsoft Teams and Microsoft Defender for Office 365 Plan 1 or Plan 2.<\/p>\n<p>  <\/p>\n<p><b>What will happen:<\/b><\/p>\n<p>  <\/p>\n<ul>  <\/p>\n<li>Security admins (with Teams admin permission) can add, delete, and view blocked external users and domains for Teams in the Microsoft Defender portal.<\/li>\n<p>Screenshot 1:<i> Image showcasing the teams block sender and block domain list in Microsoft Teams<\/i><\/p>\n<p><img decoding=\"async\" style=\"width: 400px\" alt=\"user settings\" src=\"https:\/\/cxcs.microsoft.net\/file\/ccp\/en-us\/dc95a408-4be7-48cf-abf1-144374acc09d\"><\/p>\n<p>  <\/p>\n<li>Incoming communications (chats, channels, meetings, and calls) from blocked users will be prevented.<\/li>\n<p>  <\/p>\n<li>Existing communications from blocked users will be automatically deleted.<\/li>\n<p>  <\/p>\n<li>Audit logs will track actions taken to block users for compliance monitoring.<\/li>\n<p>  <\/p>\n<li>Entry limits: Up to 4,000 blocked domains and 200 email addresses can be configured for Teams.<\/li>\n<p>  <\/p>\n<li>This applies to all Teams clients and the Defender XDR web portal.<\/li>\n<p>  <\/p>\n<li>Existing federation configurations and domain blocks in the Teams admin center remain unaffected.<\/li>\n<p>  <\/ul>\n<p><b>[What you can do to prepare:]<\/b><\/p>\n<p>  <\/p>\n<ul>  <\/p>\n<li>Enable the setting \u201cBlock specific users from communicating with people in my organization\u201d in the Teams admin center (default:  <b>Off<\/b>).<\/li>\n<p>Screenshot 2:<i>&nbsp; Image showing the teams toggle for blocking sender email addresses in Microsoft Teams<\/i><\/p>\n<p><img decoding=\"async\" style=\"width: 400px\" alt=\"user settings\" src=\"https:\/\/cxcs.microsoft.net\/file\/ccp\/en-us\/b106849c-21e7-4b6b-beaa-c7ee023ed12f\"><\/p>\n<p>  <\/p>\n<li>Enable the setting \u201cAllow my security team to manage blocked domains and blocked users\u201d in the Teams admin center (default:  <b>Off<\/b>).<\/li>\n<p>  <\/p>\n<li>Grant security team access to manage blocked domains and users in the Teams admin center.<\/li>\n<p>  <\/p>\n<li>Review internal documentation and inform helpdesk staff about this change.<\/li>\n<p>  <\/p>\n<li>Learn more: <a href=\"https:\/\/learn.microsoft.com\/microsoft-365\/security\/office-365-security\/tenant-allow-block-list\">  Tenant Allow\/Block List documentation<\/a>.<\/li>\n<p>  <\/ul>\n<p><b>[Compliance considerations:]<\/b><\/p>\n<p>  <\/p>\n<p>No compliance considerations identified, review as appropriate for your organization.<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>MC1200058 | (Updated) Microsoft Defender for Office 365: Admins can block external users in Microsoft Teams fr [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-14667","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/posts\/14667","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/comments?post=14667"}],"version-history":[{"count":0,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/posts\/14667\/revisions"}],"wp:attachment":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/media?parent=14667"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/categories?post=14667"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/tags?post=14667"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}