I am trying to implement an encryption solution using GPG, but it seems our Exchange server is blocking every message that has been encrypted. Signed messages work fine, and receiving encrypted messages also works, but as soon as i try to send an encrypted message, i get a mail from "System administrator" (wouldn't that be me? ;)) telling me that the the message couldn't be delivered, and a pretty uninformative error-code: [0x80004005-00000000-00000000]. Googling it doesn't really turn up much. I have tried disabling our av/spam detection and smtp scanner in our sonicwall, but to no avail. We also have a trend-micro mail scanner running on the exchange server, which i've also tried disabling, and it doesn't help. I've also tried checking and fixing the exchange servers mailbox store integrity, no help either. Can anyone help?