attachment problem

[schooner]

OS 10.4.9
Ibook G4
1.5 GB Ram
Web based mail for now

I sent an email with an attachment, as a 184 KB .jpeg, which opened
OK for me in the preview application. The recipient in France
couldn't open the attachment.
I opened my sent items, and instead of .jpeg, the attachment had
turned into File type: application/octet-stream.

I sent the attachment on an email to myself and it came through the
same, File type: application/octet-stream.

I sent the attachment to a friend as an acrobat file and it opened
fine. He couldn't find, or hasn't the expertise to find "File type:
application/octet-stream".

I've never had problems with jpegs. I've sent stuff back and forth to
this client in jpeg many times. I think his not being able to open
the attachment has something to do with the application/octet-stream

..jpeg
Saved from Adobe Deluxe as a jpeg
File name: LiberteLower_kb_jpeg
File size: 388kb
Came back to me (when I sent it to myself) as:
File type: application/octet-stream
Scan result: No virus threat detected.

Acrobat
Saved from Adobe Deluxe as an Acrobat File
File name: Liberte_Acrobat
File size: 2026kb
Came back to me (when I sent it to myself) as:
File type: application/octet-stream
But it opened in Preview.
Scan result: No virus threat detected.

Any input would be appreciated.

Rafael