To communicate with the Diplomacy Adjudicator you should send it a mail message in the following format:
    SIGNON pxxxx password
Where 'p' is the identifier of the power you have been assigned and 'xxxx' is the name of the game you are participating in. The power identifier is usually the first letter of the power unless there are conflicts in which case it might be the second letter. For example in the Youngstown variant, India's identifier is "N" since Italy uses "I". To enter a game that is forming, use:
    SIGNON ? password               To enter the next available game
or  SIGNON ?xxxx password [variant] Specifying the name of the game you want
or  CREATE ?xxxx password [variant] To create a new game and sign on
or  OBSERVE xxxx password           To just get the reports for a game
your password will be set to the password you specify. Note that if you use the third form above, other players wishing to enter that game will have to use the second form.

Immediately after the initial signon you should specify your preference of what powers you would like to be assigned with the command:

Where the list is a sequence of the power identifier letters. To give a set of powers equal weighting, enclose them in parenthesis or square brackets. Thus: "set preference f[ergti]a" would indicate that you really want France and really don't want Austria, but you don't care about which of the others you are assigned if you can't have France.

To take over a power that has become abandoned, you merely sign on with:

    SIGNON pxxxx password [variant]
Where 'p' is the identifier of the power you are attempting to take over.

In addition to the standard variant, supported nonstandard variants are:

    Youngstown:  A fairly common variant including Asia.
    Loeb9:       Danny Loeb's 9 player variant including Spain and Norway.
    Pure:        Each power starts with one army on a map of seven provinces.
    Chaos:       A 34 player variant in which each player gets one center.
    Britain:     England starts with six armies.
    1898:        Each player starts with only one of his home centers.
    Crowded:     Eleven players occupy all 35 centers at game start.
    Machiavelli: Uses money to support units and/or bribe others' units.
    Fleet_Rome:  Italy starts with a fleet rather than an army in Rome.
    Gunboat:     The identities of the other players are kept secret.