In your second example you are sending the filename as 'test.pgp' vs 'test.fdf' are you not?

Yes. Sending the encrypted file as "test.fdf" just confuses Acrobat.

On the Outlook end, I developed a VBA macro to automatically save the attachment as an FDF file. This seems to work OK.

I'm using Network Associates' PGP Desktop Security 7.0. When I open the test e-mail in Outlook, when I select the Save Attachment command or run the macro, I'm prompted for the pass phrase for the key I'm using.

The only flaw with the PDF::FDF::Simple module is that it doesn't seem to have a method for adding the /F key, which associates the FDF file with a PDF form.

I found a solution for associating the FDF with a PDF file:

package PDF::FDF::Simplemod;
use PDF::FDF::Simple;
our @ISA = qw(PDF::FDF::Simple);

sub _fdf_header {
  my $self = shift;
  return <<__EOT__;
%FDF-1.2

1 0 obj
<<
/FDF << /Fields 
[
__EOT__
}

sub _fdf_footer {
  my $self = shift;
  return <<__EOT__;
]
/F (test.pdf)/ID [ <id string 1><id sring 2>
] >> 
>> 
endobj
trailer
<<
/Root 1 0 R

>>
%%EOF
__EOT__
}
1;
[download]

Part of the problem seemed to be that the FDF Simple module was generating FDF headers that weren't compatible with my verison of Acrobat (5.0.5). So I generated an FDF from the PDF form so I could determine the format for the headers.