- Reject user ids containing ANSI control characters when creating a new
signing key.
- Prevent adding certificates twice when querying online sources if they
contain multiple encryption keys.
- Dedup introducers if there are multiple authenticating paths.
- When listing locals, skip the signing key.
- Check if a mail can be encrypted at all due to available certificates.
If not tell the MTA that the processing is done.
- Make `Introducer` comparable (`PartialEq`, `Eq` and `Hash`).
- minor polishing
Malte Meiboom