hello guys, i want to send an email by wizard mail.compose.message, but i want it sent by email that not in res.partner how can i achieve that, since the default odoo is using email from partner_ids

so i have condition 
1. i have customer_id field -> this will be default email that will be send by the wizard

2. i have recipient_email field -> if this field has a value (email) it will send to this email

thank you for your help :)