  The mail reader help on expressions.

    [xxx]    Means that xxx is optional and can be left out.

    <num>    A single number, eg. "1".

    <range>  Any range of numbers or a single number, ranges are noted as
             "2-4", i.e. from 2 till 4. Ranges and numbers can also be linked
             with commas as "2,4", i.e. 2 and 4.
             Examples: "1,9,5-7"  "3"  "2,4"  "2-4"

    <name>   A list of names containing player names, domain names or aliases.
             The may be separated by spaces or commas. The CC:-list has the
             same format as <name>.
             Examples: "mercade, mrpr"  "Gondor, admin"

    <file>   The name of a file to store a single message in. The filename may
             use tilde (~) notation.

