For the use of EGVP two different certificates are needed. First, a qualified signature certificate for signing messages is needed. This requirement meets the requirements of the procedural regulations (especially writing requisite). Moreover, the use of a further certificate for the end-to-end encryption is required.
This certificate is need tol open your mailbox and to encrypt and decrypt the messages (unnoticed for you). There are special requirements since version 2.6.0 of EGVP in this certificate. It has to be a so-called combination certificate (a certificate for signing, encryption and decryption at all). A certificate that meets these requirements is not included in your PKS signature card. The requirements are fulfilled by software certificates.
EGVP offers the convenient way to create software certificates and include them in the application. For EGVP this is the recommended way for using your mailbox. Details are described in the documentation of EGVP at