The following script (MoveDate) if run from a rule will add the date from the end of the subject to the start of the subject. Test it with a selected message and the test macro.
Code:
Option Explicit
Sub Test()
Dim olMsg As MailItem
On Error Resume Next
Set olMsg = ActiveExplorer.Selection.Item(1)
MoveDate olMsg
lbl_Exit:
Exit Sub
End Sub
Sub MoveDate(oItem As MailItem)
Dim sText As String
If oItem.Subject Like "Site * Alert:*" Then
sText = Right(oItem.Subject, 10)
If IsDate(sText) = True Then
oItem.Subject = sText & Chr(32) & oItem.Subject
oItem.Save
End If
End If
lbl_Exit:
Exit Sub
End Sub