* fix(notification): incorrect date header format
The date header in the email envelopes was incorrectly formatted missing a space between the `Date:` header and the value of this header. This also refactors the notification templates system allowing people to manually override the envelope itself.
* test: fix tests and linting issues
* fix: misc issues
* refactor: misc refactoring
* docs: add example for envelope with message id
* refactor: organize smtp notifier
* refactor: move subject interpolation
* refactor: include additional placeholders
* docs: fix missing link
* docs: gravity
* fix: rcpt to command
* refactor: remove mid
* refactor: apply suggestions
Co-authored-by: Amir Zarrinkafsh <nightah@me.com>
* refactor: include pid
Co-authored-by: Amir Zarrinkafsh <nightah@me.com>
