Once the campaign has been created and tested, it can be scheduled to be sent.
To send a campaign, click the Schedule button in the campaign editor. The Schedule button is not visible for remarketing campaigns, where the rules for sending are set differently.
There are three possible ways to send your campaign:

If you select an Immediate campaign sending option and click Schedule, you'll see the last final campaign recapitulation with an overview of what you're about to send, with what settings, and to whom. At this point, you have the last option to Cancel the immediate sending of your campaign. Click "Yes, send this campaign" button to send the campaign to the associated mailing list or delivery feed.
For unattended sending, the campaign will start sending depending on your settings. Simply set any date and time the campaign will be sent, and the campaign will be sent at that time.

You can also schedule several campaign deliveries for unattended sending, always with individual content, subject, delivery capping, or delivery feed. After you schedule a campaign in unattended mode, the campaign delivery is placed on a list where you can preview it, view the subject of the message, and verify the scheduled date and time of sending.
You can cancel the delivery by clicking the Cancel button.
It is not possible to edit an already scheduled campaign delivery, you can only delete it and set up/edit and schedule it again.
When scheduling unattended sending, the subject of the campaign, its content, and the delivery capping conditions are "locked".
Therefore:
Campaign recurring sending is used to set up automated campaigns that are, for example, sent daily, but only to those recipients that match the set condition on that day. Therefore, recurring sending is often combined with Delivery capping.
When setting up recurring sending, select the start (from which date the campaign should be sent regularly) and the end (until what date the campaign should be sent regularly). Next, set the sending time and period. For example, if you want your campaign to be sent every day for one year, select all days of the week in the "Repeat on" settings and choose to send your campaign every 1 week.