diff --git a/README.md b/README.md
index 297f8de..57a50af 100644
--- a/README.md
+++ b/README.md
@@ -10,6 +10,7 @@ Infrastructure as Code for managing access to MCP community resources using Pulu
 
 - **GitHub Teams**: Automatically syncs team memberships in the MCP GitHub organization
 - **Google Workspace Groups**: Automatically syncs group memberships for @modelcontextprotocol.io email accounts
+  - **Email Groups**: Groups with `isEmailGroup: true` accept emails from anyone (including external users) and notify all members. External posts are moderated for security.
 
 ## Deployment
 
diff --git a/src/config/groups.ts b/src/config/groups.ts
index 694462c..6cf782a 100644
--- a/src/config/groups.ts
+++ b/src/config/groups.ts
@@ -2,6 +2,9 @@ import { defineGroups } from './utils';
 
 // NOTE: For GitHub teams, only the first memberOf will be used as the parent team.
 // GitHub only supports one parent team per team.
+//
+// Email groups (isEmailGroup: true) accept emails from anyone (including external users)
+// and notify group members for each email.
 export const GROUPS = defineGroups([
   {
     name: 'test-parent',
@@ -12,4 +15,14 @@ export const GROUPS = defineGroups([
     description: 'Registry maintainers',
     memberOf: ['test-parent'],
   },
+  {
+    name: 'test-email-group',
+    description: 'Example email group that accepts external emails',
+    isEmailGroup: true,
+  },
+  {
+    name: 'antitrust',
+    description: 'Antitrust compliance contacts',
+    isEmailGroup: true,
+  },
 ] as const);
\ No newline at end of file
diff --git a/src/config/users.ts b/src/config/users.ts
index 95e0c66..82b00fa 100644
--- a/src/config/users.ts
+++ b/src/config/users.ts
@@ -6,4 +6,16 @@ export const MEMBERS: readonly Member[] = [
     email: 'adam@modelcontextprotocol.io',
     memberOf: ['test-child'],
   },
+  {
+    email: 'davidsp@anthropic.com',
+    memberOf: ['antitrust'],
+  },
+  {
+    email: 'mattsamuels@anthropic.com',
+    memberOf: ['antitrust'],
+  },
+  {
+    email: 'davideramian@anthropic.com',
+    memberOf: ['antitrust'],
+  },
 ] as const;
\ No newline at end of file
diff --git a/src/config/utils.ts b/src/config/utils.ts
index 14401a2..9c36942 100644
--- a/src/config/utils.ts
+++ b/src/config/utils.ts
@@ -9,6 +9,7 @@ export function defineGroups<
     name: Lowercase<string>;
     description: string;
     memberOf?: readonly (T[number]['name'])[];
+    isEmailGroup?: boolean;
   }[]
 >(groups: T) {
   for (const group of groups) {
@@ -28,10 +29,11 @@ export interface Group {
   name: GroupKey;
   description: string;
   memberOf?: readonly GroupKey[];
+  isEmailGroup?: boolean;
 }
 
 export interface Member {
   github?: string;
-  email?: `${string}@modelcontextprotocol.io`;
+  email?: string;
   memberOf: readonly GroupKey[];
 }
\ No newline at end of file
diff --git a/src/google.ts b/src/google.ts
index 25d39b0..69363c6 100644
--- a/src/google.ts
+++ b/src/google.ts
@@ -17,18 +17,25 @@ GROUPS.forEach((group: Group) => {
 
     // Maximise visibility of group. It's visible in GitHub anyway
     whoCanViewMembership: 'ALL_IN_DOMAIN_CAN_VIEW',
-    
+
     // This specifies who can add/remove members. We want this to only be via this IaC.
     whoCanModerateMembers: 'NONE',
     whoCanLeaveGroup: 'NONE_CAN_LEAVE',
     whoCanJoin: 'INVITED_CAN_JOIN',
-    
-    // We don't intend these groups to be used as mailing lists, so we set posting and viewing messages to the most restrictive settings currently available.
-    whoCanPostMessage: 'ALL_OWNERS_CAN_POST',
-    whoCanContactOwner: 'ALL_OWNERS_CAN_CONTACT',
-    // This is badly named, but actually means 'Permissions to view group messages'. See https://developers.google.com/workspace/admin/groups-settings/v1/reference/groups
-    whoCanViewGroup: 'ALL_OWNERS_CAN_VIEW',
-    
+
+    // Email groups allow anyone (including externals) to post
+    // Non-email groups are not intended as mailing lists, so use the most restrictive settings
+    // whoCanViewGroup is badly named, but actually means 'Permissions to view group messages'. See https://developers.google.com/workspace/admin/groups-settings/v1/reference/groups
+    ...(group.isEmailGroup ? {
+      whoCanPostMessage: 'ANYONE_CAN_POST',
+      whoCanContactOwner: 'ALL_OWNERS_CAN_CONTACT',
+      whoCanViewGroup: 'ALL_MEMBERS_CAN_VIEW',
+    } : {
+      whoCanPostMessage: 'ALL_OWNERS_CAN_POST',
+      whoCanContactOwner: 'ALL_OWNERS_CAN_CONTACT',
+      whoCanViewGroup: 'ALL_OWNERS_CAN_VIEW',
+    }),
+
   });
 
   group.memberOf?.forEach((parentGroupKey) => {