I'm trying to create a function that returns an email.  I want it to return a Salesforce field type Email, like you would put in an sObject, rather than a String.  The reason for this is that true email addresses are case sensitive before the @ and case insensitive after the @.  Here is the header of the function I'd like to change:

    webservice static ???.Email GetMainContactEmail(Id aid) {    <-- replace ??? with library name to qualify Email field type

Here is the test method that does not work because the function is using a String.

    public static testmethod void testGetMainContactEmailOnly() {
        Account testAccount = TestData.MakeAccount();
        Contact testContact = TestData.MakeContact(testAccount);
        System.assertEquals(testContact.Email, Utilities.GetMainContactEmail(testAccount.Id));
    }

The contact is created with a randomly generated mixed case email address consisting of 10 alphanumeric characters, '@', 10 alphanumeric characters, '.com'.  Here is the test result:

System.AssertException: Assertion Failed: Expected: 2BC8reZIC1@S1X422H1ou.com, Actual: 2bc8rezic1@s1x422h1ou.com

If anyone has a reliable alternative to trying to return the field type from the function, something that will still conform to the RFC requirements on case sensitivity, I would like to hear that also.

Thanks for your time and effort.