GUI  WEB   CLI  ...

                  |____|_____|____|

                          |

======================= Auth  ==============

                          |

...  <--|                 |

        |                 |

POP3 <--|                 |

        |-->  Fetch <-- HTTP(S)

IMAP <--|       |         |

                |         |

             Filter --> Archive --> Announce

                |

                |

               Send

                |

           -----------

           |         |

          SMTP      ....

* mail index in sqlite
* mail data in zip on the FS
* Auth: GPG
* HTTP(S) <--> JSON <--> ...
* accounts, settings, etc in sqlite
* administration via cli