A policy was not met.
CRL not available.
Available CRL is too old.
The signature is good.
The key has expired.
Can't verify due to missing key.
The key has been revoked.
The signature is bad.
The signature has expired.
A system error occurred.
Tofu conflict detected.
The signature is fully valid.
A value representing the signature status bit flags for a particular #GMimeSignature.