Hotmail & Ntl incompatible?

[tigerlelly]

My e-mails to an Ntl contact have been coming back marked 'delay' followed a few hours later by a delivery failure notice. Her e-mails to me sometimes get through but even if I tick reply they can't follow the path back. We are stumped. Until about a month ago we had no problems. I've checked to make sure that I haven't accidently blocked the address and she has done the same.Appreciate any advice.