Since GnuPG errors can be sometimes confusing we have this mechanism in QGPGME to alo collect stderr from GnuPG.

We call it diagnosics and internally it uses the auditlog mechanism. It would be nice if we could also show that in KMail. Maybe a generic error dialog in libkleo for this?

To have a reproducible case here which allows us to solve this issue we can use signing with a non VS-NfD compliant key in VS-NfD mode.

The GpgOL error is clear thanks to the diagnostics. (In english it says that vs-nfd is the problem)

In KMail the same error is more confusing:

sorry for the german screenshots i took them from a customer mail.