Use DataTypeAttribute with DataType.EmailAddress without validation

Question

Look at almost any question about [DataType(DataType.EmailAddress)] and validation and you'll find someone stating that the attribute is not for validation but to allow rendering of the property as a mailto link with DisplayFor or as an HTML 5 "email" input type with EditorFor. The only problem is the attribute does cause validation. In my view model I have the property:

[DataType(DataType.EmailAddress, ErrorMessage="Invalid e-mail address")]
[Required]
[StringLength(256, ErrorMessage = "The email address is too long")]
public string EmailAddress { get; set; }

and displayed on a registration form as:

<div>
    *E-MAIL ADDRESS
    @Html.EditorFor(m => regVM.EmailAddress)
    @Html.ValidationMessageFor(m => regVM.EmailAddress)
</div>

This renders an HTML 5 "email" type input, which is what I want and my reason for including the DataTypeAttribute. However, if I enter the value "asdf" into the email input, it displays the validation error message: Please enter a valid email address. Notice the attribute not only causes validation but also ignores the ErrorMessage I've provided (which, initially, I had not included under the belief this was not a validation attribute.) I am aware that you can use the EmailAddressAttribute to specify a custom validation message, but that's not my question.

I guess I'm looking to

1. Add to the web knowledge base that although the attribute may not be intended for validation, it sure includes it (if that is, indeed, the case)
2. Ask, "Is there is there a way to disable this validation?"
3. Get thoughts on why, if it's going to validate, which makes sense since DataTypeAttribute inherits from ValidationAttribute, does it ignore the ErrorMessage parameter? This seems like a bug. It basically says, "I'm a validation attribute...but only a little bit".

Notes: I had the unobtrusive, client-side validation enabled during my tests.

Edit
So I decided to do another test. I removed jquery.validate.js and jquery.validate.unobtrusive.js from my page. Now I can submit an invalid e-mail address and ModelState.IsValid is true; it does not validate the e-mail address format. So maybe this is a bug with the client-side validation scripts.