ShipStation can apply various actions to multiple orders and shipments in bulk.
To apply actions to order in bulk, select the orders in the Orders grid you wish to modify. Then select which action you'd like to apply by clicking either the Action button or selecting an action from the Bulk Update drop-down menu.

Once you select the desired action, follow the instructions on the screen to complete it. ShipStation will then apply the update to all selected orders.
From the Bulk Update drop-down menu, you can:
Set Ship by Date
Add a Note
Apply Shipping Preset
Set the Service
Change Shipping Account
Set the Package type
Set the order weight
Set the package size
Set the Ship From
Add Insurance
Set the confirmation type
Set the Do Not Notify Marketplace option
Select the Email Template
Select the Packing Slip Template
Set Other Shipping Options
Add Tax Identifier
With the Action buttons, you can do the following to orders in bulk:
Hold
Tag
Assign To
Print Packing Slips, Pick Lists, or Order Summaries
Mark orders as Shipped (under Other Actions)
Cancel Orders (under Other Actions)
Validate Addresses (under Other Actions)