ZF-4901: MX-Check makes not too much sence - Mailserver may accept Mails without MX-Records
Nice Feature, but according to RFC 2821 Chapter 5, a mailserver which is correctly configured must not have a MX-RR. Checking such a Server with Zend_Validate_EmailAddress::setValidateMx() may result in a negativ Result, but the Server may receive e-mails. Due too this reason the MX-Check does not really make sence.
"If no MX records are found, but an A RR is found, the A RR is treated as if it was associated with an implicit MX RR, with a preference of 0, pointing to that host." (see http://www.ietf.org/rfc/rfc2821.txt)