Enviei cerca de 150 email e deste 82 eram hotmail e outlouk e o erro reportado em todos é igual ao sdescrito.
xxxxqsb@hotmail.com host hotmail-com.olc.protection.outlook.com [104.47.42.33]
SMTP error from remote mail server after pipelined MAIL FROM:<gcbgestao@gcbarquinhense.pt> SIZE=2656: 550 5.7.1 Unfortunately, messages from [188.93.231.125] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150). You can also refer your provider to
http://mail.live.com/mail/troubleshooting.aspx#errors. [BY2NAM03FT003.eop-NAM03.prod.protection.outlook.com].
Mas só desde ontem começou a dar este erro até ontem tudo normal.
Obrigado