What action will address this issue?
Create a scheduled scaling action to scale up in anticipation of the traffic.
Change the Auto Scaling group to scale up and down based on CPU utilization.
Change the launch configuration to launch larger EC2 instance types.
Modify the scaling policy to deploy more EC2 instances when scaling up.
Explanations:
Creating a scheduled scaling action to scale up in anticipation of the traffic will ensure that the Auto Scaling group is appropriately sized at the start of each business day, addressing the delay in confirmation emails.
Scaling based on CPU utilization may not be effective in addressing the issue of delayed emails since the root cause may be queue depth rather than CPU usage.
Launching larger EC2 instance types does not necessarily address the problem of scaling to handle higher order volumes, which is the primary concern.
Modifying the scaling policy to deploy more EC2 instances when scaling up may not be sufficient to handle the expected traffic at the beginning of each day without proactive scaling actions.
I evaluate that the answer is:
Create a scheduled scaling action to scale up in anticipation of the traffic.