Thats still quite impressive!

FWIW, you can change the modified date of a file (based on "When E-mails are saved in Windows, the “Date Modified” shown in Windows Explorer is the date saved, not the date of the E-mail" from your help file)
[vba]Sub AnExample()
Dim vFile As String, vDate As Date
vFile = "C:\jefft\MailFile.xls"
vDate = Now - 20 '20 days ago
UpdateModifiedTime vFile, vDate
End Sub
Sub UpdateModifiedTime(ByVal FilePath As String, ByVal NewModifiedTime As Date)
Dim sh As Shell, sf As Shell32.Folder, fi As Object
Dim pos As Long, vPath As String, vFile As String
pos = InStrRev(FilePath, "\")
vPath = Left(FilePath, pos)
vFile = Mid(FilePath, pos + 1)
Set sh = CreateObject("Shell.Application")
Set sf = sh.NameSpace(vPath)
Set fi = sf.ParseName(vFile)
fi.ModifyDate = NewModifiedTime
Set sh = Nothing
Set sf = Nothing
Set fi = Nothing
End Sub[/vba]

As for the mention in the help file, you can feel free to keep it, or you can feel free to remove it. My suggestion says that you should remove it and get all the kudos for it (your idea, all I did was help to guide you, and you still did most of the work).

Very nice work though!