This patch allow to define custom msmtp options per email account. For
example: to change the "auth" method from "on" to "login", add
`msmtp.extraConfig.auth="login"`.
This reverts the commits
- "alot: change msmtp default command"
8e798e4c28
- "astroid: init"
736e340bde
because they include changes that break some configurations and some
options that are misplaced.
