diff --git a/e2e/src/api/specs/auth.e2e-spec.ts b/e2e/src/api/specs/auth.e2e-spec.ts
index 9174128bb8..e871691ed5 100644
--- a/e2e/src/api/specs/auth.e2e-spec.ts
+++ b/e2e/src/api/specs/auth.e2e-spec.ts
@@ -100,6 +100,12 @@ describe('/auth/*', () => {
         expect(status).toBe(400);
         expect(body).toEqual(errorDto.badRequest());
       });
+
+      it('should reject an invalid email', async () => {
+        const { status, body } = await request(app).post('/auth/login').send({ email: [], password });
+        expect(status).toBe(400);
+        expect(body).toEqual(errorDto.invalidEmail);
+      });
     }
 
     it('should accept a correct password', async () => {
diff --git a/e2e/src/responses.ts b/e2e/src/responses.ts
index f4e4193f86..80e4f76f4f 100644
--- a/e2e/src/responses.ts
+++ b/e2e/src/responses.ts
@@ -61,6 +61,12 @@ export const errorDto = {
     message: 'The server already has an admin',
     correlationId: expect.any(String),
   },
+  invalidEmail: {
+    error: 'Bad Request',
+    statusCode: 400,
+    message: ['email must be an email'],
+    correlationId: expect.any(String),
+  },
 };
 
 export const signupResponseDto = {
diff --git a/server/src/dtos/auth.dto.ts b/server/src/dtos/auth.dto.ts
index 679c944320..6488901fb6 100644
--- a/server/src/dtos/auth.dto.ts
+++ b/server/src/dtos/auth.dto.ts
@@ -5,6 +5,7 @@ import { APIKeyEntity } from 'src/entities/api-key.entity';
 import { SessionEntity } from 'src/entities/session.entity';
 import { SharedLinkEntity } from 'src/entities/shared-link.entity';
 import { UserEntity } from 'src/entities/user.entity';
+import { toEmail } from 'src/validation';
 
 export enum ImmichCookie {
   ACCESS_TOKEN = 'immich_access_token',
@@ -41,7 +42,7 @@ export class AuthDto {
 
 export class LoginCredentialDto {
   @IsEmail({ require_tld: false })
-  @Transform(({ value }) => value?.toLowerCase())
+  @Transform(toEmail)
   @IsNotEmpty()
   @ApiProperty({ example: 'testuser@email.com' })
   email!: string;
diff --git a/server/src/dtos/user.dto.spec.ts b/server/src/dtos/user.dto.spec.ts
index 683879a310..e6be3b17d1 100644
--- a/server/src/dtos/user.dto.spec.ts
+++ b/server/src/dtos/user.dto.spec.ts
@@ -38,6 +38,22 @@ describe('create user DTO', () => {
     expect(errors).toHaveLength(0);
   });
 
+  it('validates invalid email type', async () => {
+    let dto = plainToInstance(UserAdminCreateDto, {
+      email: [],
+      password: 'some password',
+      name: 'some name',
+    });
+    expect(await validate(dto)).toHaveLength(1);
+
+    dto = plainToInstance(UserAdminCreateDto, {
+      email: {},
+      password: 'some password',
+      name: 'some name',
+    });
+    expect(await validate(dto)).toHaveLength(1);
+  });
+
   it('should allow emails without a tld', async () => {
     const someEmail = 'test@test';
 
diff --git a/server/src/validation.ts b/server/src/validation.ts
index 4a8d8db866..b50491aaab 100644
--- a/server/src/validation.ts
+++ b/server/src/validation.ts
@@ -152,11 +152,14 @@ export function validateCronExpression(expression: string) {
   return true;
 }
 
-type IValue = { value: string };
+type IValue = { value: unknown };
 
-export const toEmail = ({ value }: IValue) => (value ? value.toLowerCase() : value);
+export const toEmail = ({ value }: IValue) => (typeof value === 'string' ? value.toLowerCase() : value);
 
-export const toSanitized = ({ value }: IValue) => sanitize((value || '').replaceAll('.', ''));
+export const toSanitized = ({ value }: IValue) => {
+  const input = typeof value === 'string' ? value : '';
+  return sanitize(input.replaceAll('.', ''));
+};
 
 export const isValidInteger = (value: number, options: { min?: number; max?: number }): value is number => {
   const { min = Number.MIN_SAFE_INTEGER, max = Number.MAX_SAFE_INTEGER } = options;