diff --git a/api/strategies/openidStrategy.js b/api/strategies/openidStrategy.js
index 079bed9e10..26143b226a 100644
--- a/api/strategies/openidStrategy.js
+++ b/api/strategies/openidStrategy.js
@@ -357,16 +357,18 @@ async function setupOpenId() {
           };
 
           const appConfig = await getAppConfig();
-          if (!isEmailDomainAllowed(userinfo.email, appConfig?.registration?.allowedDomains)) {
+          /** Azure AD sometimes doesn't return email, use preferred_username as fallback */
+          const email = userinfo.email || userinfo.preferred_username || userinfo.upn;
+          if (!isEmailDomainAllowed(email, appConfig?.registration?.allowedDomains)) {
             logger.error(
-              `[OpenID Strategy] Authentication blocked - email domain not allowed [Email: ${userinfo.email}]`,
+              `[OpenID Strategy] Authentication blocked - email domain not allowed [Email: ${email}]`,
             );
             return done(null, false, { message: 'Email domain not allowed' });
           }
 
           const result = await findOpenIDUser({
             findUser,
-            email: claims.email,
+            email: email,
             openidId: claims.sub,
             idOnTheSource: claims.oid,
             strategyName: 'openidStrategy',
@@ -433,7 +435,7 @@ async function setupOpenId() {
               provider: 'openid',
               openidId: userinfo.sub,
               username,
-              email: userinfo.email || '',
+              email: email || '',
               emailVerified: userinfo.email_verified || false,
               name: fullName,
               idOnTheSource: userinfo.oid,
@@ -447,8 +449,8 @@ async function setupOpenId() {
             user.username = username;
             user.name = fullName;
             user.idOnTheSource = userinfo.oid;
-            if (userinfo.email && userinfo.email !== user.email) {
-              user.email = userinfo.email;
+            if (email && email !== user.email) {
+              user.email = email;
               user.emailVerified = userinfo.email_verified || false;
             }
           }
diff --git a/packages/api/src/auth/domain.spec.ts b/packages/api/src/auth/domain.spec.ts
index c84d32cbcd..4f6c25ec51 100644
--- a/packages/api/src/auth/domain.spec.ts
+++ b/packages/api/src/auth/domain.spec.ts
@@ -6,15 +6,27 @@ describe('isEmailDomainAllowed', () => {
     jest.clearAllMocks();
   });
 
-  it('should return false if email is falsy', async () => {
+  it('should return true if email is falsy and no domain restrictions exist', async () => {
     const email = '';
     const result = isEmailDomainAllowed(email);
+    expect(result).toBe(true);
+  });
+
+  it('should return true if domain is not present in the email and no domain restrictions exist', async () => {
+    const email = 'test';
+    const result = isEmailDomainAllowed(email);
+    expect(result).toBe(true);
+  });
+
+  it('should return false if email is falsy and domain restrictions exist', async () => {
+    const email = '';
+    const result = isEmailDomainAllowed(email, ['domain1.com']);
     expect(result).toBe(false);
   });
 
-  it('should return false if domain is not present in the email', async () => {
+  it('should return false if domain is not present in the email and domain restrictions exist', async () => {
     const email = 'test';
-    const result = isEmailDomainAllowed(email);
+    const result = isEmailDomainAllowed(email, ['domain1.com']);
     expect(result).toBe(false);
   });
 
diff --git a/packages/api/src/auth/domain.ts b/packages/api/src/auth/domain.ts
index 06710ac6d7..00bcf91787 100644
--- a/packages/api/src/auth/domain.ts
+++ b/packages/api/src/auth/domain.ts
@@ -3,6 +3,12 @@
  * @param allowedDomains
  */
 export function isEmailDomainAllowed(email: string, allowedDomains?: string[] | null): boolean {
+  /** If no domain restrictions are configured, allow all */
+  if (!allowedDomains || !Array.isArray(allowedDomains) || !allowedDomains.length) {
+    return true;
+  }
+
+  /** If restrictions exist, validate email format */
   if (!email) {
     return false;
   }
@@ -13,12 +19,6 @@ export function isEmailDomainAllowed(email: string, allowedDomains?: string[] |
     return false;
   }
 
-  if (!allowedDomains) {
-    return true;
-  } else if (!Array.isArray(allowedDomains) || !allowedDomains.length) {
-    return true;
-  }
-
   return allowedDomains.some((allowedDomain) => allowedDomain?.toLowerCase() === domain);
 }