sub mail {
        local $self = shift;
        local $dbh = $self->param('dbh');
        my $q = $self->query();
        local $session = $q->param('session');
....
}

##</code><code>##

sub mail {
        my $self = shift;
        my $dbh = $self->param('dbh');
        my $q = $self->query();
        my $session = $q->param('session');
}