To add a new carrier, from your store's Admin Dashboard, choose Settings > Shipping.
Scroll down the page to the Flat Rates section and click the Add Rate button.
On the new Flat Rate page add your carrier's name to the Label field.
DO NOT check the Active checkbox. Your new method must be Inactive, or it will show up as a shipping option to your customers.
Scroll down to the Advanced Settings section and choose Other from the Gateway dropdown.
Click the blue Save button at the top right of the page to save the method.
You can now access an order by choosing Orders > Process Orders from the Admin Dashboard.
Access a specific order by clicking its Order ID.
Scroll down to the Tracking section. You can enter the tracking number and choose your new shipping method from the Shipping Method dropdown. It will be listed under the heading Other.
Finish any additional steps you have on the order and click the Complete Order button at the top right of the order to send the Shipped Email to the customer containing the tracking information.
You can also modify the Shipped Email to display the tracking information for you new carrier.
Editing Email Text
Editing the text of this email (including adding any Tracking Links) is handled via your websites FTP connection. Making that change is outlined in THIS article.
Adding Tracking Links
Not all shipping carriers support the automated tracking links that are built into the Volusion OrderHasShipped.asp email templates. To make sure your customers can access their tracking information without the automated link, you may want to include the tracking code and links to relevant shipping carriers.
To add shipping carrier links beneath the tracking number, include the following HTML code under the "$(TrackingNumbers)" email variable once you access this template via the FTP:
USPS: <a href="http://www.usps.com">www.USPS.com</a>
UPS: <a href="http://www.ups.com">www.UPS.com</a>
DHL: <a href="http://www.dhl.com">www.DHL.com</a>
FedEx: <a href="http://www.fedex.com">www.FedEx.com</a>
Specific Carrier: <a href="http://www.specificcarrier.com">www.SpecificCarrier.com</a>
Now customers will see something resembling this in your email:
Carrier Tracking Number