For Odoo.sh databases, Use the Mails tab to access the Mail Catcher

https://www.odoo.com/documentation/18.0/administration/odoo_sh/getting_started/branches.html#mails

Hi,

Yes, it's possible to test emails in a neutralized Odoo database safely.

If you want to prevent emails from going to real contacts but still test the flow, you can overwrite all res_partner emails (excluding internal users) using this SQL query via psql:

UPDATE res_partner

SET email = 'test.yourname@example.com'

WHERE email IS NOT NULL

  AND id NOT IN (

    SELECT partner_id FROM res_users WHERE partner_id IS NOT NULL

  );

This updates only external contacts, leaving internal user-linked partners untouched.

Hope it helps.