------------------
        Incoming Mail-> |--+   helium       <-----------| Outgoing Mail  |
                          -|----------------                     |
                          ||     LMTP      |                     |
                          -|----------------                     |
                          |+>    Cyrus    +----------------+     |
                          |+>    Imapd    ||---->+         |     |
                          |+>  (hafnium)  ||     |         |     |
                          -|--------------|-     |         |     |
                          ||Authentication||    2|        1|     |
                          |+<    SASL    <+|     v         ^     |
                          ------------------     |Receiving|  |Sending|
                                                     |           |
                                                 +--------------------+
                                                 |     Mail Client    |
                                                 |    (Thunderbird)   |
                                                 +--------------------+