Method 1: Disabling Emails in Follow-up Levels
1. Go to: Accounting → Configuration → Follow-up Levels
2. Locate the follow-up levels (e.g., 15 days, 30 days, 60 days).
3. Uncheck the Send E-mail option for the specific follow-up levels you want to disable.
4. Save the changes.

Method 2: Disabling Scheduled Actions (Debug Mode)

1. Activate Developer Mode: Go to Settings → Technical → Scheduled Actions
2. Find and disable scheduled actions related to follow-ups (e.g., "Send Follow-ups").
3. Toggle off or delete the scheduled action to stop automatic follow-up emails.Additional Consideration:
4. If your Odoo system has automated actions, check under Settings → Technical → Automated Actions to ensure no other triggers are sending follow-up emails.