It sounds like Odoo is pulling the salesperson's signature instead of the sender's. This may be due to the email template settings. Check Settings > Technical > Email Templates  and ensure that the signature variable pulls from the current user (${user.signature}) rather than the assigned salesperson. If the issue persists, consider customizing the email template or checking role-based permissions. Implementing email signature automation can help ensure the correct signature is applied dynamically for each user. Hope this helps!