/OVERDRAFT=value
       /NOOVERDRAFT

    The /OVERDRAFT qualifier specifies the amount of message storage
    by which the account can exceed its message storage quota. If the
    account is currently using less than its storage quota, then a
    new message can be stored provided that it will not result in the
    account's storage exceeding the sum of its storage and overdraft
    quotas.

    The /NOOVERDRAFT qualifier is equivalent to specifying
    /OVERDRAFT=0 and indicates that the account has no overdraft
    quota.

    By default, this quantity is specified in units of kbytes;
    however, the SET STORAGE_UNITS command can be used to change
    the units used.

    The maximum value is 4 gigabytes minus 1. If the value specified
    exceeds the maximum, the value is set to zero (no overdraft
    quota).