SYSNAME

  This global config-string is mandatory. It must be specified and
it must be unique for each system/MB.
  It's the name of the system in fully qualified domain-format; it
must match the pattern "#[a-z0-9_].#['-a-z0-9._]".

  NOTE  that  in  contrast to previous version of UMS this may not
contain "@" anymore. Use only the part after "@".

  NOTE  also  that  now  there's only one global SYSNAME. Expoters
cannot use this anymore, but there is a new string MSGID.


MSGID

  now  there  is  always  a  global  config-string  "MSGID", which
defaults to

    ( MSGID $serial @ $sysname )

  This  default  usually  doesn't  need to be changed. But you can
specify an optional MSGID for each exporter.
  The  MSGID  string  is  used  to create message-ids whenever new
messages  are  created.  Exporter-specific  MSGIDs allow to choose
alternate  formats  for differents exporters. However this is only
possible  when  the  new  message  is  accessibly  by  exactly one
exporter.  If  there  is  more  than one exporter, e.g. in case of
crosspostings,   multiple-recipient   mails  or  several  possible
exporters for one mail, then the globals MSGID will be used.
  MSGID must use one of "$serial" or "$serial8". These are virtual
config-strings,  giving  consecutive decimal numbers from 1 trough
99999999  each  time  a  message-id is generated. They are used to
make message-ids unique.
  The differences between $serial and $serial8 is that $serial can
have  1  through  8  digits, whereas $serial8 always has 8 digits.
$serial8 has leading zeroes whenever neccessary.

  NOTE that the result of MSGID must match the global AKA pattern!
It's considered invalid otherwise.