In my work account on a Microsoft Exchange server, we have public keys for all users in LDAP. Sometimes an encrypted email message from a known user fails to decrypt, instead showing a panel with no menu: "Thunderbird cannot decrypt this message". Errors are sporadic: for a few senders, all messages fail to decrypt on my Thunderbird, while for a few other senders, all messages successfully decrypt. For most senders, it seems to randomly depend on the particular message. In one odd case, a chain of replies can be successfully decrypted up to a point, and from there on, all replies fail to decrypt for me. We've looked into all the settings, and we've tried variations where someone sends me an encrypted message without signature, then another with encryption and signature. Nothing seems to consistently cause or avoid the error, it just seems to happen randomly. Can someone recommend a way to diagnose the problem, for example debug logs? It would also be helpful to try manually decrypting the raw received message using openssl. Is it possible to find it somewhere in the `~/.thunderbird/` area?