How to set the main email account to send emails?

I’m switching my SMTP gateway to send emails from CiviCRM but for now I still have both. And even though I thought everything was sent from the newly configured service in https://domain.net/civicrm/admin/setting/smtp?reset=1 I can see in logs that automatic reminders are still sent from the previous gateway and not from the new one.

Have I missed something? Do I need to configure an account elsewhere in CiviCRM for automatic reminder or any transactional email or is this just a normal delay?

Any ideas?

Guillaume