AOL emails bouncing back certain domains

The following problem has been acknowledged and yet, has been persisting for weeks unfortunately: "Apparently, email messages ( that with the @aol.com domain ) bounces to and in some occasions, from multiple domains and comes up with Error 521. This has been escalated already. As of writing, we are still working towards a possible solution on this. We would like to apologize for the inconvenience this issue might have caused, but let us assure you that higher level technicians have been assigned to getting this resolved."