sylpheed GPG compatibility

[Guy]

I've been playing arround with Sylpheed some more, and it is fantastic.

I got it to work together with kmail.
But one problem remains, i have some friends using windows,
mainly Eudora and PGP 6.5.x.  I set up a test here duplicating that with vmware.

And it appears that messages encrypted with sylpheed and GPG can't be decrypted with Eudora+PGP.  old-fashioned encryption like with kmail works...

Any suggestions?

Kind regards

Guy Van Sanden