diff --git a/lib/services/microsoft-graph-mail.ts b/lib/services/microsoft-graph-mail.ts
index 9987a94..329b3f8 100644
--- a/lib/services/microsoft-graph-mail.ts
+++ b/lib/services/microsoft-graph-mail.ts
@@ -17,8 +17,21 @@ const GRAPH_API_BASE = 'https://graph.microsoft.com/v1.0';
  * Get a configured Axios instance for Microsoft Graph API
  */
 async function getMicrosoftGraphClient(mailCredentialId: string): Promise<AxiosInstance> {
-  // Get fresh access token
-  const tokenResult = await ensureFreshToken(mailCredentialId);
+  // Look up the mail credential to get userId and email for token refresh
+  const account = await prisma.mailCredentials.findUnique({
+    where: { id: mailCredentialId },
+    select: {
+      userId: true,
+      email: true,
+    },
+  });
+
+  if (!account) {
+    throw new Error('Mail credential not found for Microsoft Graph client');
+  }
+
+  // Get fresh access token using userId + email
+  const tokenResult = await ensureFreshToken(account.userId, account.email);
   
   if (!tokenResult || !tokenResult.accessToken) {
     throw new Error('Failed to obtain valid access token for Microsoft Graph API. The account may need to be re-authenticated with Mail.Read and Mail.Send permissions.');