As you go through the ShipMagic process, one of the first questions your are asked is:
"When is the latest the package can arrive?"
One of the choices is "I'm Flexible" - this means you are flexible about when the package can arrive, and you will receive options for all of the delivery dates, rather than just for a particular timeframe, such as 3 days.
Later in the ShipMagic process we ask you, "Have Carrier Pickup Your Package at Home?"
In this case, "I'm Flexible" means the system will provide rates that include home pickup as well as rates that are for drop-off.