Our client wants to add the Tracking Code directly on the mail that the consumer receive

Customer :

We already have bought your Fedex plugin a few weeks ago.
Now, our client wants do that?

From what I saw on your FAQ it seems possible only with the Stamps plugin, but is it compatible with Fedex?

Support :

Kindly make sure that the tracking pin option is enabled in the plugin settings.

Also, make sure you are using the latest version of the Plugin.