..
with My::Config;

## some runtime information, eventually for the trait's method
has validDomain => (
    isa => 'Str',
    is => 'rw',
);

has alarmMailsTo => (
    traits => ['ConfigEmail'],
    conf_key => 'ALARM_MAILS_TO'
    attr_valid_domain => 'validDomain'  ## give attr name to trait
    isa => 'ArrayRef[Str]',
    is => 'rw',
);
..