Mailflow roadmap since version 0.33.18
                                                                               +-------------------<------------------+
  +-----------+                                                                |  +-------------+                     |
  | toss      +----------------------------------------------------------------+  |             +-> AreaMgr/FileMgr >-+
  | inbound   |                 FTN format                                     |  | postnetmail |
  | mail      +-------------------------------------------------------------+  |  |             +-> storenet >-------> Messagebase
  +-----------+                                                             |  +--+ check PING  |
                                                                            |  |  |             +---------------+
  +-----------+                                          +-----------+      |  |  |  email/UUCP +--+            |
  | stdin     |                                          |           +---------+  +-------------+  |            v
  | pipe      +-----------------------+------------------+  rfc2ftn  |      |                      |            |
  | rnews     |                       |                  |           +------+                      |            +----> mailer outbound
  +-----------+                       |                  +-----------+      |                      v            |
                                  RFC |                                     |                      |            ^
  +-----------+                format |                                     |     +-------------+  |            |
  | scan news |                       |                                     |     |             +---------------+
  | from inn  +-----------------------+                                     +-----+  postecho   +-> storeecho >------> Messagebase
  | server    |                       |                                           |             +--+            |
  +-----------+                       |                                           +-------------+  |            |
                                      |                                                            |            |
                      +-------------+ |              +---------------------------<-----------------+            |
  +-----------+       |      no ISP +-+              |                                                          ^
  | scan JAM  +-------+ email   ISP +------------------------------------------+  +-------------+               |
  | msgbase   +-----+ +-------------+                |                         |  |             |               |
  | for new   +---+ |                                |                         +--+  postemail  +--------------------> SMTP
  | messages  +-+ | | +-------------+                v                         |  |             |               |
  +-----------+ | | +-+ echomail    +------------------------------------+     |  +-------------+               |
                | |   +-------------+                |                   +--------------------------------------+
                | |                                  |   +-----------+         |                                |
                | |   +-------------+  FTN format    |   |           +---------+  +-------------+               |
                | +---+ news gate   +----------------+---+  ftn2rfc  |         |  |  internal   +--------------------> INN feed
                |     +-------------+                    |           +------------+  newsspool  +--------------------> pipe rnews
                |                                        +-----------+         |  |             +--------------------> UUCP batch
                |     +-------------+                                          |  +-------------+               |
                +-----+     to UUCP +------------------------------------------+                                |
                      | netmail     +-> tracker >---------------------------------------------------------------+
                      +-------------+