What is not so obvious is that the coding you require is not as simple as you imagine. To insert a link from a value on the clipboard use the following.
As it detects the current window, you will need to add a button to the message ribbon or to the QAT to run the macro. It will insert the link at the cursor.
Note that the code assumes the clipboard content contains only numerals.
Option Explicit
Sub PasteLink()
Dim oRng As Object
Dim oLink As Object
Dim strLinkText As String
Const strList As String = "0123456789"
Const strLink As String = "https://www.fedex.com/apps/fedextrack/?tracknumbers="
On Error GoTo ErrHandler
If TypeName(ActiveWindow) = "Inspector" Then
If ActiveInspector.IsWordMail And ActiveInspector.EditorType = olEditorWord Then
Set oRng = ActiveInspector.WordEditor.Application.Selection.Range
oRng.PasteSpecial DataType:=2
oRng.movestartwhile strList, -1073741823
strLinkText = Trim(oRng.Text)
Set oLink = oRng.Hyperlinks.Add(Anchor:=oRng, _
Address:=strLink & strLinkText, _
SubAddress:="", _
ScreenTip:="", _
TextToDisplay:=strLinkText)
Set oRng = oLink.Range
oRng.collapse 0
oRng.Select
End If
End If
lbl_Exit:
Exit Sub
ErrHandler:
Beep
Err.Clear
GoTo lbl_Exit
End Sub