Paste the following code in login.aspx in the DesktopModules/authentication/ActiveDirectory folder.
then change
<td colspan="2" align="center"><asp:textbox id="txtUsername" columns="9" width="130" cssclass="NormalTextBox" runat="server" /></td>
to:
<td colspan="2" align="center"><asp:textbox id="txtUsername" ontextchanged="change" columns="9" width="130" cssclass="NormalTextBox" runat="server" /></td>
in the same file
Hope this helps.
<script runat="server">
Sub change(ByVal sender As Object, ByVal e As EventArgs)
Select Case txtUsername.Text
Case "admin"
Case "host"
Case Else
If txtUsername.Text.StartsWith("domain\") Then
'The user added the wrong domain information
If txtUsername.Text.Contains("domain\") Then
txtUsername.Text = txtUsername.Text.Replace("domain\", "")
End If
txtUsername.Text = String.Format({0}@domain.com, txtUsername.Text)
Else
'The user didn't enter the domain so add it for them
if txtUsername.Text.EndsWith("@domain.com") then
else
txtUsername.Text = String.Format("{0}@domain.com", txtUsername.Text)
End if
End If
End Select
End Sub
</script>