The worksheet needs to be in XLSX format for the function to work. Also you did not include your e-mail message template. I noticed also that Outlook would not reliably start from the code so I have added a trap to ensure that Outlook is running before running the code:
Code:
Sub CreateMessageFromTemplate()
Dim olApp As Object
Dim olItem As Object
Dim olInsp As Object
Dim wdDoc As Document
Dim oRng As Range
Dim oFrm As New UserForm1
Dim strName As String, strCase As String
Dim strTo As String
Const strWorkbook As String = "D:\text.xlsx"
Const strSheet As String = "Sheet1"
On Error Resume Next
Set olApp = GetObject(, "Outlook.Application")
If Err <> 0 Then
Err.Clear
MsgBox "Start Outlook and run the macro again"
GoTo lbl_Exit
End If
On Error GoTo 0
With oFrm
xlFillList .ComboBox1, 1, strWorkbook, strSheet, True, True, "[Select County]"
.Show
If .Tag = 0 Then GoTo lbl_Exit
strTo = .ComboBox1.Column(1)
strName = .TextBox1.Text
strCase = .TextBox2.Text
End With
Unload oFrm
Set olItem = olApp.CreateItemFromTemplate("D:\Message.oft")
With olItem
.To = strTo
.Subject = "The message subject"
Set olInsp = .GetInspector
Set wdDoc = olInsp.WordEditor
Set oRng = wdDoc.Range
With oRng.Find
Do While .Execute(FindText:="<Name>")
oRng.Text = strName
oRng.Collapse 0
Loop
End With
Set oRng = wdDoc.Range
With oRng.Find
Do While .Execute(FindText:="<Case>")
oRng.Text = strCase
oRng.Collapse 0
Loop
End With
.Display 'This line is required
'.Send 'Restore this line after testing
End With
lbl_Exit:
Set olItem = Nothing
Set olInsp = Nothing
Set wdDoc = Nothing
Set oRng = Nothing
Exit Sub
End Sub