Is ebMS appropriate for systems like webmail?

Has there been consideration in ebMS 3 or any of the
ebXML framework standards for the use case of 
a 'transfer' between two parties using the same
web-based system such as webmail? I guess here the
'transfer' is actually little or no more than a change
in properties of a file on a server (the 'payload').
I hear from one webmail development company that
it is obvious to still use the SMTP header with IMAP
or the like for the sake of standards conformance,
even though they are hardly necessary for the
'transfer' so maybe the same considerations would
apply to, say, an ebMS header - but the whole use
case seems to be quite appropriate for special
consideration as technology moves forward this way.

Stephen Green