Miguel,
to copy the document use something like this:
<br/>
Dim s As New NotesSession<br/>
Dim doc1 as NotesDocument, doc2 As NotesDocument, ...<br/>
'Repeat this block for each document:<br/>
Set doc1 = doc.CopyToDocument( s.CurrentDatabase )<br/>
doc1.FieldYouWantToChange = "NewValue"<br/>
Call doc1.Save( True, False, True )<br/>
If you want it done when the doc is mailed place the code in Postsend form event, you don't need an agent.
Tell me, Miguel, how this relates to the project Code library?
Hope this helps,
Mb¤