By default SIMMS auto-ships your sales orders, invoices, RMAOUTs, and RTVPUTs. This means these documents are given the status of Shipped when saved and they are not listed in the Shipping Manager. Auto-shipping is useful if you do not want to process your shipments in SIMMS.
However, you can manually process your shipments in SIMMS with the Shipping Manager. By doing this you create a detailed record of your shipping activities directly in SIMMS. This includes information about what you shipped, what needs to be shipped, the method your items were shipped by and so on.
To manually process your shipments in SIMMS you need to enable this feature in Global Settings.