Envelope

- Licence change from GPL-3.0-or-later to LGPL-3.0-or-later.

- fix addresses for older python patched versions (< 3.12.3, < 3.11.?) 45

- reworked s/mime cryptography

- resilience against missing libmagic (useful on a contained environment)
- better SMTP retries 35
- better typing 31
- fix: attachment included while signing only (without sending)

- fix: loading headers not encoded with utf-8
- fix: better S/MIME detection 29
- drop Python 3.9 support
- SMTP HELO FQDN

- experimental [XARF](http://xarf.org/) reports reading
- disguised addresses parsing