diff --git a/app/api/courrier/account/route.ts b/app/api/courrier/account/route.ts
index 0731c47..467d16f 100644
--- a/app/api/courrier/account/route.ts
+++ b/app/api/courrier/account/route.ts
@@ -242,11 +242,56 @@ export async function DELETE(request: Request) {
     if (!account) {
       return NextResponse.json({ error: 'Account not found' }, { status: 404 });
     }
+
+    // Find all calendar sync configs linked to this mail credential
+    const syncConfigs = await prisma.calendarSync.findMany({
+      where: {
+        mailCredentialId: accountId,
+      },
+      include: {
+        calendar: true,
+      },
+    });
+
+    // Delete calendars and sync configs associated with this account
+    // This prevents orphaned calendars when a mail account is deleted
+    for (const syncConfig of syncConfigs) {
+      console.log(`[COURRIER] Deleting calendar ${syncConfig.calendar.name} (${syncConfig.calendar.id}) associated with deleted account ${account.email}`);
+      
+      // Delete the calendar (events will be cascade deleted)
+      await prisma.calendar.delete({
+        where: { id: syncConfig.calendarId },
+      });
+      
+      // Sync config is already deleted by cascade, but we can also delete it explicitly
+      try {
+        await prisma.calendarSync.delete({
+          where: { id: syncConfig.id },
+        });
+      } catch (error) {
+        // Ignore if already deleted by cascade
+      }
+    }
+
     // Delete from database
     await prisma.mailCredentials.delete({ where: { id: accountId } });
+    
     // Invalidate cache
     await invalidateFolderCache(session.user.id, account.email, '*');
-    return NextResponse.json({ success: true, message: 'Account deleted' });
+    
+    // Invalidate calendar cache for this user
+    try {
+      const { invalidateCalendarCache } = await import('@/lib/redis');
+      await invalidateCalendarCache(session.user.id);
+    } catch (error) {
+      console.error('Error invalidating calendar cache:', error);
+    }
+    
+    return NextResponse.json({ 
+      success: true, 
+      message: 'Account deleted',
+      deletedCalendars: syncConfigs.length,
+    });
   } catch (error) {
     console.error('Error deleting account:', error);
     return NextResponse.json({ error: 'Failed to delete account', details: error instanceof Error ? error.message : 'Unknown error' }, { status: 500 });