open fun resolveMX(name: String, handler: Handler<AsyncResult<MutableList<MxRecord>>>): DnsClient
Try to resolve the MX records for the given name.
name - the name for which the MX records should be resolved
handler - the io.vertx.rxjava.core.Handler to notify with the io.vertx.rxjava.core.AsyncResult. The handler will get notified with a List that contains all resolved io.vertx.rxjava.core.dns.MxRecords, sorted by their io.vertx.rxjava.core.dns.MxRecord#priority. If non was found it will get notified with an empty java.util.List. If an error accours it will get failed.
Return
a reference to this, so the API can be used fluently.