<form id="a1">
  <input type="email" name="xy">
</form>

<form id="a2">
  <input type="email" name="xy">
</form>

$('#a1').bootstrapValidator({
    message: 'This value is not valid',
    fields: {
        xy: {
            validators: {
                emailAddress: {
                    message: 'Invalid mail-address'
                }
            }
        }
    }
});

$('#a2').bootstrapValidator({
    message: 'This value is not valid',
    fields: {
        xy: {
            validators: {
                emailAddress: {
                    message: 'Invalid mail-address'
                }
            }
        }
    }
});