better handling of unusable pubkeys
one of the subscribers to our list had an expired key and this is what happened:
- the expiration date for the signing was renewed but not the encryption keys'
- schleuder received an email and tried to process it
- subscribers sorted before this subscriber received the email
- when it tried to send to the subscriber, it failed with "unusable public key" error
- it bounced the message and stopped sending email for the rest of subscribers
- on inspection, schleuder's pubring for the list had renewed the key but the encryption keys were missing (removed by cleanup i guess)
so apart from the user error, i think schleuder should've handled this more gracefully than to distribute an email to some subscribers and not others. the error message also doesn't mention which one was the unusable key, so debugging is more difficult.
maybe it needs to check if all the keys are ok before sending? i'm busy for the next weeks but i can try writing a patch :)