Here is a list of macros for the FILE send handler that I found on Jan Tielens' Bloggings.
This is something I find everyone googling for quite often, so thought of putting it up here for quick reference.
For the details of each of the macros, please see Jan Tielens' Bloggings
%datetime%
%datetime_bts2000%
%datetime.tz%
%DestinationParty%
%DestinationPartyID%
%DestinationPartyQualifier%
%MessageID%
%SourceFileName%
%SourceParty%
%SourcePartyID%
%SourcePartyQualifier%
%time%
%time.tz%