Mail notification for starting certification campaign

Hi,

I'm configuring an attestation campaign for an AD Group membership which must be approved by employee's managers.

I want to send a notification when the campaign starts to every manager with the link to the portal, but don't want to send a notification for every attestation case of his/her users.

I have enabled on Designer the RequestApproverByCollection parameter, but I see that notifications are sent on a scheduled basis.

Is there any chance to maintain RequestApproverByCollection parameter enabled for reminders, but at the same time send a starting campaign notification to every manager with the detail, like the type of campaign, group to review, start and end...?

I haven't seen the ootb option to perform this. Maybe to implement a custom process, but don't know which table to use just to send one notification for manager.

Thanks!