This feature is not supported by your smartcard: mail.box

I’m receiving this error when trying to send signed email to internet recipient. My internet certificate is on a smartdcard in CardMan 6121 reader, card is Siemens, CardOS V4.3B. The DLL I had to select in notes is siecap11.dll.

The behavior is the same in v 7.0 and 7.0.2 of the Notes Client.

What is the issue?