We have just upgraded to hibernate-validator 5.x (from 4.x).

One of our IT fails with the following email:
sjmw0bnvfqqmorqii0zba0ksyvp8sdda8i6t8erjep4t3fymzmx4iv01dhe3adv@2oanppnisfqyd1prvfzrki7qopefaotb1898bmokq1xmcvms7jrdzynliqphi0m.com

In this case the call to toAscii is broken down in two cycles:

• 2oanppnisfqyd1prvfzrki7qopefaotb1898bmokq1xmcvms7jrdzynliqphi0m
• .com

The last cycle will throw an IllegalArgumentException(
"Empty label is not a legal name") in IDN.toASCIIInternal

Failing test case:

	@Test
	public void testEmailWith63CharacterDomainPartIsValid() {
		// Domain part should allow up to 255
		isValidEmail( "foo@" + stringOfLength( 63 ) + ".com" );
	}

I guess this was broken in HV-1005 - @Email incorrectly flags emails with 64 character length local-part as invalid Complete where some of the code was rewritten by @hardy.ferentschik