Mails to specific domain always encrypt as PGP Partitioned

Hello,

I just saw a really wired behaviour one a client machine.

Here is the layout:

Windows 7, Outlook 2010, PGP Desktop 10.2 (Client will be updated soon).

Encryption policies target specfic domains, action is "ecrypt to list of keys" and prefer PGP/MIME.

For one domain (let's say example.com), all e-mails are encrypted as PGP Partitioned. Not matter which key I use. Even if I use my own key.

On the other hand, if I encrypt e-mails to the key of the example.com domain ans send it to myself, the mail is encrypted PGP/MIME.

So the only difference is which domain the e-mail is sent to.

Can anybody explain this or know a solition?

Thank you in advance!