ntl are aware of the problems and are working on it. The problem has been posted to the status page and is also given on IVRs:
"Ntlworld email customers may currently experience difficulties sending emails to anyone with an email address ending in AOL.com. Ntl are aware of this issue and are working with AOL to resolve this as soon as possible. Please be advised that our technical support representatives will be unable to resolve or provide any further details on this issue."
http://www.ntl-isp.ntl.com/ServiceSt...px?FaultID=358
(While this message states AOL since that was the initial symptom, they are aware of the MAPS issues)