You can select the priority for a campaign as High or Normal.
For this, go to Campaign > new > Launch Builder.
Create the campaign > select action
All messages with priority high will be put in front of the queue when processing messages for a given date.
Broadcasts are always injected as normal priority.
If a campaign has been rescheduled then a number of attempts will try to send email again.

Note: – If an email is pending but if the number of attempts has been reached, the message will not be sent.