Draft: email: Finish cleanup and enable as advanced app
Lot of testing is pending. Hence the draft status.
Highlights:
- Simplify code greatly drop some minor features when code is complex.
- Show DNS entries to be added manually.
- Setup common aliases such as 'postmaster'.
- Drop feature to enable/disable aliases as discussed.
- Generate DKIM keys.
- Implement backup/restore.
- Implement basic functional tests.
- Different icon.
- Enable app as advanced app.
- Open port for managesieve protocol.
- Run redis daemon as it is required by many rspamd features.